Iraqi Foreign Minister Tariq Aziz arrived in Moscow last night in search of a political opening to a cease-fire in the 32-day-old Persian Gulf War, amid growing signs that an allied ground and amphibious assault to oust Iraq from Kuwait may be imminent.

President Bush continued to duck questions about the timing of a ground war, but he said the gulf conflict could end "very, very soon."

A flurry of diplomatic activity, resembling in some respects the last days before war erupted on Jan. 17, coincided with intensified ground clashes along Saudi Arabia's northeastern border and the reported massing of 31 amphibious ships in one unspecified area of the Persian Gulf.

A Marine official in Washington said the 31 ships, which carry about 18,000 Marines and their combat equipment, represent the war's entire complement of amphibious assault vessels and were "scattered around" until recently for security.

Two U.S. soldiers were killed and six were wounded by mistaken fire from U.S. helicopters as infantry patrols attacked Iraqi forces in seven separate early morning engagements. The patrols were backed by artillery, armor and AH-64 Apache helicopters.

The casualties, which came when an Apache helicopter fired Hellfire antitank missiles at a Bradley Fighting Vehicle and an M-113 armored personnel carrier during a cross-border fight in the predawn darkness, brought to 10 the number of U.S. troops killed by "friendly fire" out of a total of 14 killed on the ground since the war began.

In one of the heaviest artillery bombardments of the war, the Army's 1st Infantry Division on Saturday fired more than 1,000 rockets and eight-inch howitzer shells into positions across the Saudi-Iraqi border, according to a pool report made available yesterday.

During a morning walk on the beach in Kennebunkport, Maine, the president, who was confronted by an anti-war protester during church services, said he had been mourning for the Kuwaiti people since their country was invaded by Iraq Aug. 2. "And I hope we can get an end to that suffering very, very soon," he said. "I think we will."

In Paris, French Foreign Minister Roland Dumas asserted that coalition forces were "on the eve, or just before the eve, of the ground offensive," and said a specific date had already been selected. But French Defense Minister Pierre Joxe said hours after the Dumas interview that the allies had agreed only on a general time frame. ABC News, meanwhile, reported that Turkish President Turgut Ozal said he expected ground combat would begin this week.

Like Joxe, Marine Brig. Gen. Richard I. Neal, deputy chief of operations for the U.S. Central Command in Riyadh, denied that any specific date had been established.

Bush, asked whether Dumas was right about a starting date, accused reporters of sounding like their satirized counterparts in a recent comedy routine on NBC television's "Saturday Night Live." " 'Hey, tell us how we can help the Iraqi soldiers the most?' " Bush joked. "I mean, I'm not in that business -- come on."

At the Pentagon, officials said the last U.S. ground forces arrived in their assembly areas Wednesday and are prepared for combat at any time. Elements of the Army's 3rd Armored Division, part of the tank-heavy VII Corps that is expected to lead a major ground thrust, had been delayed by "one slow boat" carrying equipment from Germany, but all units are now "locked and cocked" for battle, an official said. In a possible small intimation of things to come, a photographer traveling with that division told colleagues the soldiers received a rare treat: they dined on steak last night in their forward positions.

One official said discrepancies among public statements on a starting date may reflect semantic rather than substantive differences among allied spokesmen. The official, who asserted "there probably is a provisional date," said Bush may have delegated the launching of ground and amphibious operations to Gen. H. Norman Schwarzkopf, the top allied commander in Saudi Arabia. Defense Secretary Richard B. Cheney told reporters traveling with him last week that Bush might set a "window" of several days and give Schwarzkopf flexible authority to act within it.

Conflicting pressures within the alliance -- to show openness to diplomacy on the one hand and determination not to compromise the U.N. objectives on the other -- were also cited by officials to explain the contradictory public statements. Some analysts also noted the Pentagon's professed intention to use "tactical deception" to achieve maximum surprise against entrenched Iraqi forces.

Aziz, the Iraqi envoy, spent 90 minutes yesterday with his Iranian counterpart before departing for Moscow on a special Aeroflot flight. He traveled overland from Baghdad to Tehran to avoid flying through allied combat air patrols. Iranian Foreign Minister Ali Akbar Velayati, who returned to Tehran from Moscow on Saturday, made no public statement after his meeting with Aziz. Sees Gorbachev Today

Aziz told reporters in Tehran that his government had "taken our step and now is the turn of the other side to show its goodwill." He was scheduled to meet with Soviet President Mikhail Gorbachev today.

In Washington, administration officials acknowledged what Bush called a "question mark" about Moscow's intentions but continued to express confidence that Iraq would find no gap to exploit between the U.S. and Soviet positions.

Calling Gorbachev's role "a constructive one," Bush said "he knows very well that the objectives spelled out by the United Nations -- and the Soviet Union was an important part of this -- must be met in their entirety."

Secretary of State James A. Baker III, predicting that Gorbachev would brook no departure from U.N. resolutions calling for Iraq's immediate and unconditional withdrawal from Kuwait, asserted that the United States would welcome a Soviet-brokered settlement of the war.

"If the Soviets can get the Iraqis to pull out of Kuwait unconditionally, rapidly, totally, more power to them," Baker said in an interview broadcast on Cable News Network.

But Baker, apparently reflecting a U.S. belief that the Soviets may seek credit for an Iraqi withdrawal, added, "I think if it happens now it's just not going to be because someone has been talking to the Iraqis." Scowcroft's Response

Brent Scowcroft, Bush's national security adviser, responded sharply to Saturday's suggestion by Soviet special envoy Yevgeny Primakov that some way must be found for Iraqi President Saddam Hussein to save face.

"Mr. Primakov has been to Baghdad now three times," Scowcroft said in an interview broadcast on CBS's "Face the Nation." "He's always been searching for this elusive withdrawal with dignity. . . . Nobody has ever been able to describe what such a package would be. {Saddam} cannot be rewarded for the terrible things that he has perpetrated in the gulf."

Bush, who denounced Baghdad's conditional offer of withdrawal Friday as "a cruel hoax" and said "there's nothing new here," appeared to find some virtue in the initiative yesterday.

"The only good news out of that," he said, "was for the first time they talked about withdrawal, and they did not reassert their position that Kuwait was Province 19 {of Iraq}. And that's positive. They should have done it on about the first week in August."

Scowcroft, however, discounted the Iraqi move as "another attempt to create confusion and dissension within the coalition." He said there were no "ancillary activities going on which would make it look more serious." Investigation Begun

Neal, briefing reporters near the U.S. Central Command's headquarters in Riyadh, said an investigation has been begun to determine how the U.S. Apache helicopter could have fired at friendly armored vehicles. First indications were that the pilot was disoriented and had his aircraft pointed south instead of north when he saw the U.S. vehicles, a military source said.

A pool report from the Saudi border said the dead soldiers, who came from the 1st Infantry Division, were crew members of a Bradley Fighting Vehicle conducting "screening operations" just inside the Iraqi border at about 1 a.m. Saudi time.

"This is taking place at night," Neal emphasized. "It's taking place with moving vehicles. It's just a very difficult environment."

Although U.S. helicopter pilots last fall reported trouble keeping oriented in the featureless Arabian desert while wearing night-vision goggles, Neal said early reports did not suggest the goggles were behind yesterday's error.

A Pentagon official said yesterday that U.S. forces have made more than a dozen operational changes to avoid friendly fire, including the use of special markings that are visible in the thermal imaging sights of some U.S. warplanes. Iraqi forces, the official said, have no such thermal equipment. Officials declined to specify other measures for fear of aiding the Iraqis.

A British spokesman, Group Capt. Niall Irving, acknowledged, meanwhile, that a bomb dropped by a British warplane went astray and slammed into a residential neighborhood in the Iraqi town of Fallujah during an attack on bridges Wednesday.

The Iraqi government had announced that 130 civilians were killed during bombing Thursday against bridges in the town, 40 miles west of Baghdad. There was no explanation for the discrepancy in days.

Yesterday's early-morning clashes came as U.S. forces stretched along the Saudi-Kuwaiti and Saudi-Iraqi borders became more aggressive in night patrols, seeking out Iraqi positions across the frontier and assaulting targets with artillery and helicopters.

In addition to helicopters, the early-morning ground engagements matched U.S. tanks and personnel carriers, vehicle-mounted TOW antitank missiles and field artillery against Iraqi tanks, personnel carriers and multiple rocket launchers, the U.S. Command said.

Neal said the Apache helicopters destroyed three Iraqi tanks, three BTR-60 wheeled armored personnel carriers and a multiple rocket launcher in addition to blasting apart a bunker and ammunition dump on the Iraqi side of the front. Iraqi Soldiers Surrender

After their bunker was destroyed, a group of 10 Iraqi soldiers came out with their hands up and surrendered to a hovering Apache helicopter, he reported. They walked across the border with the Apache thumping along behind, he reported.

A senior U.S. military source said the U.S. forces initiated all seven of yesterday's engagements after spotting Iraqi patrols on both sides of the border or fixed Iraqi positions on the Iraqi side. Pentagon officials said the intensified probes were aimed at keeping U.S. forces sharp and their Iraqi counterparts in a state of constant anticipation of a large-scale allied ground assault.

Another 10 Iraqi soldiers surrendered in a separate engagement, bringing to 20 the number of prisoners taken in the early-morning hours, Neal said. There was no immediate explanation for a conflicting pool report from the Saudi border, which said units of the 101st Airborne Division (Air Assault) took 41 Iraqi prisoners in the morning engagements. In all, U.S. and coalition forces have taken 1,263 Iraqi soldiers prisoner, more than half by defections, according to a count by Saudi officials who have responsibility for them.

Since Saddam's conditional withdrawal proposals Friday, however, what had been a steady trickle of defections has come to a halt. The Saudi military spokesman, Col. Ahmed Robayan, said allied commanders have no explanation for the change.

Staff writers Dan Balz in Kennebunkport, Nora Boustany in Jordan, William Drozdiak in Paris and staff researcher Ralph Gaillard Jr. in Washington contributed to this report. Cody reported from Riyadh.