DUBAI, UNITED ARAB EMIRATES, SEPT. 4 -- An Iranian Silkworm surface-to-surface missile hit the southern coast of Kuwait early today, causing concern in Kuwait that Iran may escalate its attacks against Iraq's closest ally in the gulf war.

A senior official in Tehran denied that Iranian forces had fired any missile at Kuwait.

{In Washington, however, Pentagon officials, citing intelligence sources, confirmed that the missile was a Silkworm and that it was fired from Iranian-held territory in Iraq, Washington Post staff writer Molly Moore reported. Officials said it was the first hostile use of a Chinese-made Silkworm in the seven-year-old gulf war.}

The missile, which has a range of 50 miles, fell before daylight on an uninhabited stretch of coast two miles from Kuwait's main oil loading terminal, according to a Kuwaiti Defense Ministry statement and shipping sources in the gulf.

Two Kuwaiti tankers flying the American flag were at the oil terminal awaiting a U.S. naval escort to take them out of the gulf.

But U.S. and western sources said the missile did not appear to be aimed at the American-registered ships and, if fired by Iran, probably was intended to harass and intimidate the Kuwaiti government.

In New York, United Nations Secretary General Javier Perez de Cuellar announced that he will travel to Tehran and Baghdad next week to press for compliance with a July 20 Security Council cease-fire resolution. {Details, Page A29.}

As the diplomatic effort to end the war advanced, Iraq's military command announced that its warplanes struck a "large naval target," the term Baghdad uses for a tanker, off the coast of Iran. If confirmed, it would be the 13th strike on shipping in the gulf since the resumption of the tanker war last Saturday.

Iraq also said it had hit Iranian oil installations at Ahvaz and Agha Jari in southwestern Iran and an oil pumping station in the Imam Hassan area. There were also reports that the two belligerents fired artillery at each other's cities along the southern war front.

An Iraqi communique said Iraqi forces were enforcing their "legitimate rights to deny the Iranian regime all economic resources" and that the attacks would continue "so long as the Iranian regime persists in its aggression on our country and refuses to abide to the international will to establish peace."

Meanwhile, the Italian Cabinet reversed course today and voted to send warships to the region to join the United States, Britain and France in protecting shipping. An Italian container ship was attacked early yesterday by a gunboat firing rocket-propelled grenades.

The captain of the Italian vessel suffered a broken leg and one of the 22 Italian crewmen was hit by shrapnel.

Italy, Spain and Japan protested to Iran this week about attacks on their vessels in what has been the most intense week of violence against merchant shipping since.

In Tehran, meanwhile, Iranian Parliament Speaker Ali Akbar Hashemi Rafsanjani told an assembly at prayers today at Tehran University that Iran was not responsible for the reported missile attack on Kuwait and added cryptically that the United States knows who fired the missile.

Rafsanjani, in the familiar rhetoric of the public statements at prayers, warned that the longer the United States stays in the gulf, the harder it will be to get out.

Shipping officials along the 550-mile waterway between the Strait of Hormuz and Kuwait were braced for a fresh round of Iranian retalitory attacks on shipping tonight as a U.S. Navy-escorted convoy of reflagged Kuwaiti energy ships neared the Strait of Hormuz.

The convoy, which had anchored off Bahrain last night, was sighted this afternoon off Doha and was expected to clear the strait tonight.

The three Kuwaiti ships, the Gas Princess, the Gas Queen and the supertanker Townsend, were flanked by the destroyer USS Kidd and the guided missile cruiser USS Reeves.

The next escort mission out of the gulf is expected next week when the reflagged oil tankers Surf City and Chesapeake City have completed oil loading at the Kuwaiti port of Ahmadi and rendezvous in international waters with U.S. warships.

U.S. efforts to broaden western protection for international shipping in the gulf were boosted by the Italian Cabinet vote.

Italy, which earlier refused a U.S. request to send mine sweepers to the gulf, had persisted in a policy of deference to U.N. peace efforts when yesterday's attack by a gunboat demonstrated the threat to Italian shipping.

More than 40 percent of Italy's oil supplies are transported through these waters.

A Cabinet statement said that Foreign Minister Giulio Andreotti has asked Arab governments to provide support facilities in the gulf for Italian naval vessels.

Speaking after the Cabinet meeting in Rome, Andreotti, who has opposed such a move in the past, said he still believes that naval escorts are a "debatable" strategy and added that he believes Iran has no desire to attack Italian ships.

But Defense Minister Valerio Zanone, referring to the attack on the Italian flag freighter Jolly Rubino, told reporters in Rome, "Faced by the new situation which was created yesterday, the Navy will see to guaranteeing . . . the protection of merchant vessels."

Zanone said Italy's decision was a "defensive action in the name of principle and freedom of navigation."

The Italian naval deployment, which is not expected to begin for about a month, does not "conflict with Italy's commitment to supporting the U.N. {cease-fire} resolution," he added.

The captain of the Jolly Rubino, Guido Manfredino, recovering in a hospital here, told reporters today that the attack occurred just after midnight yesterday when a single gunboat appeared out of the darkness.

"I saw the boat with four men," Manfredino said. "At least one of them carried a bazooka. A big explosion followed and caused panic and confusion in the ship. We were all scared. I ran and broke my leg."

Asked who he thought was responsible for the attack, Manfredino told CBS News later, "Everybody knows who is using this system in the war -- everybody knows."

Shipping officials said the freighter was hit in the crew quarters area by six rocket-propelled grenades, which are fired by shoulder-mounted weapons that resemble World War II-style bazookas.