DUBAI, UNITED ARAB EMIRATES, OCT. 15 -- In its first successful missile strike on Kuwaiti territory, Iran today blasted a 10-by-13-foot hole in a U.S.-owned supertanker anchored off Kuwait's main oil port, setting the ship ablaze within sight of four other tankers that had arrived Tuesday under U.S. Navy escort.

U.S. officials in the region and in Washington said they believed the Iranian missile was a Chinese-made Silkworm fired from Iranian-controlled territory on Iraq's Faw Peninsula, about 50 miles to the north.

Kuwait immediately protested the attack to the United Nations. A Kuwaiti Defense Ministry statement said, "Kuwait holds Iran responsible for this act."

The missile attack presented the Reagan administration with a new threat of escalation in the Persian Gulf, where U.S. forces last month took military action against Iran when a mine-laying vessel threatened another anchorage in the central gulf used by U.S.-flag oil tankers and warships.

In addition, the missile struck a few miles from where the U.S. Navy was preparing to moor a second ocean-going barge rigged and armed as an offshore U.S. "fort" near Kuwait -- which has not granted U.S. basing facilities for aircraft or warships engaged in the protection of Kuwaiti shipping.

Three other long-range missiles, two of them identified as Silkworms, were fired at Kuwaiti territory last month, one of them landing harmlessly on a beach near an oil refinery complex in the same area where today's missile struck.

A Kuwaiti Foreign Ministry official was quoted as saying, "This aggression is a continuation of the attacks which Iran has carried out against Kuwait despite international efforts to convince it to accept a cease-fire in the war."

Iran did not publicly acknowledge launching the attack today, but gave extensive coverage on state-run television to film footage of the blazing tanker released by Kuwait's Information Ministry.

The missile slammed into the tanker Sungari at 5:04 a.m. as it rode at anchor about nine miles off Kuwait's Mina al Ahmadi oil terminal. Residents near the port reported hearing a massive explosion that shook windows and sent a column of black smoke and flames towering into the dawn air.

The ship was flying the Liberian flag, but its nominal corporate owner, OMI Sungari Transport Inc. of Monrovia, Liberia, is listed by Lloyd's of London as a subsidiary of Ogden Marine International Corp. of New York.

Ogden is a major U.S. independent shipping concern operating 24 tankers worldwide on charters to oil companies and national governments, according to shipping industry sources.

An Ogden vice president, Peter Long, reached in New York by telephone, said, "I would characterize the damage as serious," but added that none of the crew was injured. The explosion and fire took five hours to extinguish as flaming crude oil flowed out of a ruptured forward tank on the ship's starboard side.

The Sungari was laden with about 200,000 tons of crude when struck and was scheduled to load more crude at a deep-water terminal 25 miles off Kuwait before leaving the gulf.

Long would not disclose the destination of the ship or the ownership of the crude oil on board. Lloyd's shipping records indicated that the Sungari has hauled crude oil between the gulf and ports in Europe and Singapore this year.

Kuwait charters a number of oil tankers to feed its international oil refining and marketing operations in Europe and the Far East.

Because the Sungari is registered in Liberia, a tax haven for the international shipping industry, it is not entitled to U.S. naval escort under current U.S. policy.

Reagan administration officials have reiterated as recently as this week their intention to protect only those tankers registered under the U.S. flag. Kuwait has reregistered 11 of its tankers as American through a U.S. oil conglomerate purchased by Kuwait's national oil company.

But the presence of U.S.-flag ships in the anchorage where Iran's powerful missile fell raised the immediate question of whether the attack would draw a U.S. military response.

President Reagan, asked this morning in Washington whether the United States would respond to the attack, said, "I haven't had any conversation as yet with the {Joint} Chiefs . . . . Our policy is still that we're going to defend ourselves if we're attacked."

Last month, U.S. military forces attacked an Iranian mine-laying vessel, the Iran Ajr, while it was sowing large contact mines in an anchorage used by U.S. ships off Bahrain. U.S. officials justified the attack by saying Iran had committed a hostile act that put in jeopardy U.S.-flag vessels that either anchored in or passed through the anchorage.

Iran's use of a Silkworm in the attack focused attention once again on the missile threat against U.S. forces and Arab states. U.S. officials, who detected Silkworm batteries overlooking the Strait of Hormuz last year, made it clear to Iran that even the activation of the Silkworm's fire-control radars would be considered a hostile act against U.S. forces nearby.

The U.S. warship convoy that arrived off Kuwait on Tuesday escorted four Kuwaiti tankers to Kuwait's territorial waters. Due to Kuwait's sensitivity over maintaining its national sovereignty, U.S. warships are prohibited from entering Kuwaiti waters. The warships "drop off" the convoys at the entrance to Kuwait's ship channel, in international waters.

Meanwhile, Iraqi warplanes struck Iranian targets last night and today, including an oil tanker, the Pegasus 1, near Kharg Island and the Imam Hassan oil loading platform in southwestern Iran.