Two U.S. laser-guided bombs killed scores and perhaps hundreds of civilians yesterday in an attack on what Iraqi authorities said was a suburban Baghdad air raid shelter, but which U.S. officials insisted was a hardened bunker used as a military command center.

The attack at 4:30 a.m. (8:30 p.m. Tuesday EST) by one or two F-117A "stealth" fighters intensified international concerns about the relentless allied bombing in the Persian Gulf War, putting U.S. and allied officials on the defensive as they sought to place responsibility for the deaths on Iraqi President Saddam Hussein for endangering his people.

"The loss of civilian lives in time of war is a truly tragic consequence," White House press secretary Marlin Fitzwater said. "It saddens everyone to know that innocent people may have died in the course of military conflict." Although U.S. officials said they do not know why hundreds of civilians were inside an ostensibly military facility, Fitzwater said Saddam's "willingness to sacrifice civilian lives . . . {to} further his war aims" may have been a factor.

Western correspondents in Baghdad counted at least 40 bodies, including many women and children, from the smoking wreckage of the building. Iraqi Foreign Minister Tariq Aziz late yesterday said the building appeared to have contained 400 people. Earlier, Iraqi authorities said as many as 1,000 people had been in the facility, with at least 400 killed and many others burned or injured in what would be the worst incident of civilian casualties in the war.

In what appeared to be a carefully orchestrated U.S. response to the tragedy, military officials confirmed the bomb strike within hours of the attack. Attempting to prove that the demolished facility was a command bunker, they released drawings made from satellite photos and referred to clandestine U.S. "intercepts" of Iraqi military communications, a subject usually considered top secret.

The Pentagon, while vowing additional blows at command and control facilities, also pledged to reconsider how to reconcile its stated policy of minimizing civilian casualties with its declared aim of pounding hundreds of military targets in Iraq and Kuwait.

"It looks like civilians were hurt here. We are going to examine our consciences very closely to determine if we can't do something in the future to preclude that," Lt. Gen. Thomas Kelly, operations director for the Joint Chiefs of Staff, told reporters at the Pentagon.

A senior Pentagon official said late last night that another Iraqi command center is operating from the basement of the Al Rashid Hotel in Baghdad, where Western reporters and other foreigners are staying. Their presence will keep it from becoming a target, the official said.

Several U.S. officials said the bomb shelter had been placed on the allied target list months ago after intelligence experts concluded it was a leadership bunker designed to shelter senior Iraqi officials. That conclusion was based in part on interviews with foreign engineers who modified the building, one of about 20 such bunkers believed scattered in neighborhoods around the Iraqi capital, officials added.

Asked whether it was possible that the facility had still been in use as a "privileged sanctuary" for the Iraqi elite when it was bombed, Kelly said, "Anything's possible." But he said he had no information about any dual use of the structure.

Grisly television footage of charred bodies and wailing survivors was the most vivid reminder in four weeks of war that more than 67,000 allied sorties have wreaked enormous devastation in Iraq and occupied Kuwait. Videotape of the procession of bodies carried on stretchers from the smoldering building shocked viewers in the United States and abroad, and left U.S. officials struggling to explain how the "smart" weapons so exuberantly lauded for their precision could have such tragic consequences.

Yesterday's tragedy rekindled a debate over conduct of the war. Late yesterday, the United States and its allies blocked a move for the U.N. Security Council to hold a public session on the war and instead voted to debate Operation Desert Storm in a closed meeting today, the first time since 1975 that the public and media have been barred from the council's deliberations. U.N. Secretary General Javier Perez de Cuellar, who has criticized the scale of the air campaign, expressed "profound regret" about the Baghdad attack, a spokesman said.

The most bitter official Iraqi statement on the Baghdad bombing came from Aziz, who asked Perez de Cuellar to "condemn this savage crime," which he said "adds to the blackened criminal record of the American and Zionist aggression."

Soviet Sees 'Hope'

In Moscow, a Soviet spokesman quoted special envoy Yevgeny Primakov as saying his talks with Saddam in Baghdad this week had given "cause for hope" about a negotiated settlement to the month-old war. But the spokesman offered few details except to say that Aziz will come to Moscow, probably Sunday, for further talks, including a session with Soviet President Mikhail Gorbachev.

U.S. officials again said they encourage Soviet efforts to persuade Saddam to relinquish Kuwait. But Fitzwater said that an Iraqi pledge to withdraw is not sufficient to stop the war. "We want to see massive withdrawal," he added.

Although the deaths in Baghdad dominated yesterday's war news -- virtually excluding all other subjects at the British, Saudi and U.S. military briefings -- officials said that continuing fair weather had permitted more than 2,800 sorties, including 700 against targets in Kuwait and 200 against the Republican Guard. U.S. pilots reported destroying four transport aircraft and a helicopter on the ground, while British warplanes destroyed a missile fuel plant in central Iraq and five Astro II multiple rocket launchers, according to a spokesman.

In Ruweished near the border between Jordan and Iraq, Jordanian refugees fleeing Kuwait said yesterday that 30 of their group were killed and 24 wounded when allied planes attacked their bus, the Associated Press reported. Sudanese, Iranian and other refugees said they had seen attacks on other buses and civilian traffic elsewhere inside Iraq. They were unable to say if there were any casualties in those incidents.

The fatal strike in the Iraqi capital came from two GBU-27 2,000-pound penetrating bombs with delay fuzes that are designed to pierce more than 10 feet of concrete before detonating, Pentagon officials said yesterday. Riding a laser beam pointed at the building by a U.S. pilot, the munitions crashed through the roof within 20 feet of the aiming point, the officials added.

"From a military point of view, nothing went wrong. The target was struck as designated," Marine Brig. Gen. Richard I. Neal said in Riyadh, Saudi Arabia. "From a personal point of view, I'm outraged that civilians might have been placed in harm's way, and I blame the Iraqi government and the Iraqi leadership for that."

Pentagon officials said the facility had been built as an air raid shelter in the mid-1980s during the Iran-Iraq war. Later in the decade, it was converted to a military command and control bunker, with a 10-foot-thick concrete ceiling reinforced with steel sheeting, according to Capt. David Herrington, deputy director of intelligence for the Joint Chiefs of Staff.

The building also had been hardened to protect against electromagnetic pulse, or EMP, an effect from nuclear blasts that can ruin communications and other electronic equipment, Herrington said. Surrounded by a chain-link fence topped with barbed wire, the facility's roof also had been painted with camouflage patterns, officials said.

Occupying an entire block in a southwest Baghdad neighborhood of low-slung houses, the facility sits across the street from a school and about 100 yards from a mosque, according to television footage and Pentagon drawings of the area. Successful allied air strikes on military headquarters in downtown Baghdad had forced the Iraqis to disperse their command centers to more remote sites, Herrington said.

A senior Pentagon official last night said that earlier in the war the bunker had been used as a communications "node" to transmit orders originating elsewhere in Baghdad. U.S. intelligence had not "really seen any activity out of this bunker until the last two or three weeks," when Iraqi officers turned it into "an active command and control structure . . . that was communicating with the leadership within the KTO {Kuwaiti Theater of Operations}," Neal said.

Military Vehicles 'Seen'

Satellite reconnaissance and other intelligence means indicated in recent days that military cars and other vehicles typically used by senior Iraqis were parked outside the building, U.S. officials said last night, although one official added that no satellite images had been taken within at least 24 hours before the attack. Military personnel were also seen entering and leaving, Kelly said.

But officials were at a loss to explain how hundreds of civilians had entered the building undetected, or whether the facility had been used as a combined air raid shelter and command headquarters. And once again, U.S. officers found themselves explaining why a war intended to eject the Iraqi army from Kuwait seemed to focus so intensely on Baghdad.

"That's the head. That's the brain. That's where the missions come from," Kelly said. "If the Iraqi army is going to mount a multi-divisional attack and come out of their fortifications and head south into Saudi Arabia, that's where those orders would come from."

Defense Secretary Richard B. Cheney led the U.S. effort to deflect criticism by focusing the blame on Saddam's conduct throughout the war and before. "Saddam might now be resorting to a practice of deliberately placing civilians in harm's way," Cheney said in a speech to the U.S. Chamber of Commerce.

Cheney said he had "no way of knowing" whether that was the case in this instance. "But we do know that he had previously placed hundreds of foreign civilians, held hostage all last fall, at strategic sites throughout Iraq," Cheney added. "We do know that he's threatened prisoners of war at strategic targets throughout Iraq. We do know that he is placing military equipment in civilian areas, especially in Kuwait, but also in Iraq."

Cheney said that practice includes placing two MiG-21 fighters next to an ancient pyramid near the city of Ur, northwest of Basra, which he described as the "oldest continuously inhabited city on Earth" and the site of valuable archeological ruins dating back to 2700 B.C. He said the evidence was based on satellite photos obtained yesterday morning.

Kelly estimated that roughly 50 to 100 Iraqi fighters are now sheltered in civilian areas. Although they are unprotected and would make easy targets, U.S. raiders had refrained from destroying them because of concern about collateral damage, the general said. "One disadvantage in having your MiG parked outside of Joe's farm is it's a little bit difficult to get it back to the airfield to take off," he added.

Cheney also raised the possibility that some of the recent damage to civilian sites in Baghdad had resulted from Iraqi antiaircraft artillery fire.

At the White House, Fitzwater repeatedly suggested that the victims of yesterday's bombing had been put in the targeted building deliberately. "Why were people taken to a military target?" he asked. Questioned further, he replied, "They were told to get there some way. Somebody told them to go there."

Herrington, reiterating the avowed allied policy of avoiding non-military areas, added, "The safest place for an Iraqi civilian is at home in his bed."

U.S. officials faced persistent questioning about whether the deaths of so many civilians would affect the allied coalition or international opinion toward the United States. Could Saddam, Fitzwater was asked, gain a public relations victory?

"I think everyone loses when civilians die," he replied. "It is a truly tragic situation . . . . But I think Saddam loses in this sense because I think it dramatizes to the world once again just how ruthless he is." He said the United States occupies "the high ground" of the war morally, claiming allied pilots have gone out of their way to avoid civilian damage. "I think you'll see Saddam losing from this by every standard."

Fitzwater also dismissed suggestions that yesterday's raid could strengthen criticisms of the war from the Soviet Union and other countries. Moscow has been particularly outspoken recently in questioning "hether the allied coalition has exceeded the U.N. mandate to drive Iraqi forces from Kuwait, and instead may be bent on destroying Iraq.

Confident of Acceptance

Although U.S. officials had no hard evidence to support suggestions that Iraqi authorities may have deliberately put civilians inside a military target, they were confident that Saddam's actions in this and past conflicts would lead the public to accept their version of events.

"The assumption here is that that in any war there are going to be civilian casualties," one official said. "Unfortunately, this is one of those incidents. But Saddam Hussein's track record is so horrendous . . . that this points the finger back in the other direction. . . . I think people will wake up and say this is what he's done all along."

President Bush, who learned of the attack yesterday morning, had no comment about the incident and appeared in public only to unveil his new highway program.

At the Pentagon, Kelly repeatedly questioned whether reports from Baghdad about the casualties were accurate. "We don't have a free press there asking hard questions like you do here," he told reporters. But Cable News Network correspondent Peter Arnett, who broadcast some of the more vivid descriptions of the catastrophe, said that his report had not been subjected to censorship for the first time since the war began Jan. 17.

Kelly also expressed skepticism about the facility. "It was striking to me," the general said, that a sign near the building "looked very new and said 'bomb shelter' in English." According to witnesses, the sign also had Arabic printing.

Pressed repeatedly on how U.S. intelligence was certain that the building had been used as a command headquarters, Kelly and Herrington refused to describe how the evidence was gathered or even to acknowledge the communications intercepts divulged by Neal in Riyadh six hours earlier.

Voicing uncertainty about when the civilians had entered the building, Kelly said, "We can't watch anything 24 hours a day. That country is the size of California."

Iraqi military infrastructure permeates virtually all of that large country, officials added. Cheney said that it was not until the war began that "the sheer size and magnitude of the investment he made in the military" fully registered on him and others.

Staff writers Ann Devroy, E.J. Dionne Jr., Barton Gellman, John M. Goshko and R. Jeffrey Smith in Washington, Michael Dobbs in Moscow, Nora Boustany in Amman and staff researcher Lucy Shackelford contributed to this report.