SEA ISLAND TERMINAL, KUWAIT, OCT. 22 -- An Iranian Silkworm missile slammed into this offshore oil loading platform today, setting its overflow tanks ablaze, injuring three workers and thrusting Arab states in the Persian Gulf closer to open confrontation with Iran.

Kuwait's defense minister, Salem Sabah, said this afternoon that the Silkworm was fired from Iranian-held territory on Iraq's Faw Peninsula. A Defense Ministry spokesman denounced the attack as "another aggression against Kuwait."

The missile smashed into the center of the platform at 10:49 a.m. {3:49 a.m. EDT} with a thunderous boom and sent up a 300-foot column of smoke. Shrapnel from the warhead shredded pipes and mechanical equipment used in oil loading operations.

The damage to the offshore facility, which normally handles one-third of Kuwait's oil output and can handle up to 80 percent, did not appear to be severe. But the attack, following direct hits on two tankers here last week, was the third consecutive and accurate Silkworm strike on targets in Kuwaiti waters, emphasizing the threat posed by the Iranian missiles 40 miles to the north.

Twenty Kuwait Petroleum Co. workers were said by officials to have been on the platform this morning, but most escaped injury. The injured workers were evacuated to a Kuwait Petroleum hospital, where two were admitted for "superficial burns," according to one medical official.

Firefighting tugs from Kuwait's Shuaiba Port sent up a fountain of seawater to douse the flaming crude oil. Tug captains could be heard on marine radio complaining that they could not get close enough to the blaze as a stiff breeze whipped blinding black smoke around the terminal.

Kuwait defense forces on Failaka Island north of here saw the missile streak overhead, but the defense minister did not say whether they had tried to shoot it down with antiaircraft missiles, as defense forces tried to do unsuccessfully against two Silkworms last week.

Western officials had said earlier this week that Kuwait was redeploying its American-made Hawk antiaircraft missiles to Failaka Island in hopes of marshaling an effective air defense against incoming Silkworms.

Kuwait's Foreign Ministry summoned the Iranian charge d'affaires to lodge a "strong denunciation" of the attack. Minister of State for Foreign Affairs Saoud Oseimi told the Iranian official that the "serious attack was unwarranted and had unveiled Iran's resolve to drag nonbelligerent countries of the region to this tragic war.

"Kuwait holds Iran fully responsible for those aggressions and their consequences," Oseimi said.

Saudi Arabian Defense Minister Sultan bin Abdul Aziz telephoned his Kuwaiti counterpart following the attack and said Saudi military forces were prepared to stand by Kuwait's armed forces to face Iranian aggression, Kuwait's state news agency reported.

By early afternoon the fire on the platform was out, and Kuwait Petroleum officials were inspecting the damage to the terminal, which sits nine miles off the Ahmadi oil complex.

From a small boat that reached the waters adjacent to the terminal, reporters could see a firefighting tug pouring water over the center of the platform and its crude oil loading arms. A Kuwaiti military helicopter hovered above the 1,000-foot-long loading pier, which is connected to land storage tanks by underwater pipeline.

Kuwaiti coast guard vessels patrolled the waters near the terminal, and a half-dozen oil tankers were riding at anchor between Sea Island and the Ahmadi refinery.

No oil tankers were loading when the missile struck. Oil company officials have shepherded oil tankers away from loading facilities to safer anchorages on the days that Iran has launched other missiles.

No crude oil is stored at the terminal, and the bursting Silkworm warhead ignited only a small amount of oil in the "slop" tanks where the overflow from loading operations is dumped.

It was unclear tonight what structural damage was inflicted by the missile, but Silkworm warheads, capable of carrying 1,000 pounds of explosives, are capable of inflicting extensive shrapnel damage to the kind of steel piping, pumps and valves that comprise the oil terminal.

Kuwait's port authority was broadcasting navigational warnings to ships tonight, advising them that "the Sea Island has no lights, it is blacked out."

Last Thursday, in the first successful Silkworm strike on a Kuwaiti target, Iran missile batteries 50 miles north of here ripped a massive hole in the U.S.-owned Liberian-flag oil tanker Sungari, anchored little more than a mile from here.

A second Silkworm was launched 24 hours later and tore into the bridge tower of the U.S.-flag tanker Sea Isle City as it was maneuvering to take on crude oil at this terminal. The missile blast blinded the American captain and wounded 16 other crewmen.

The missile strikes prompted the United States to mount its first retaliatory attack on Iran, smashing Iran's Rostam oil platform in the southern gulf with 1,000 rounds of naval artillery shells.

Iran reported today's missile strike on Tehran radio, but did not claim responsibility for the attack. An Iranian military commander said Iran planned to announce a "general mobilization" next week to ask "everyone who can to take part" in a struggle against the United States, according to Tehran's Ettelaat newspaper.

In Washington, a State Department spokeswoman said, "We condemn Iran's naked aggression and expect that the international community will move urgently to address the situation."

A Pentagon spokesman said the attack did not involve U.S. forces in the region.

As the attack occurred, four U.S. warships were hundreds of miles to the south escorting two U.S.-flagged Kuwaiti tankers toward the Strait of Hormuz. The convoy passed safely through the strait this afternoon.