KUWAIT (AP) _ U.S. military authorities weighed the possibility of sending minesweepers to the waters off this Persian Gulf nation after a mine blew a hole in the hull of an American-flagged and Navy-escorted supertanker.

Engineers prepared to inspect the damage done to the Kuwaiti supertanker, which was renamed the Bridgeton when it was reflagged, to determine if it can be repaired here.

In Washington, the Pentagon considered sending minesweepers to the site of Friday's explosion, which came during the maiden voyage in a landmark U.S. effort to assert navigational freedom in the gulf. There are no minesweepers among the 17 U.S. Navy vessels in and around the strategic waterway.

Salvage executives reported today that two rusty mines have been sighted by passing ships in waters south of where the Bridgeton struck a mine.

Senior Pentagon officials, speaking on condition of anonymity, said a decision on dispatching minesweepers was pending.

The captain of one of the Navy warships in the gulf said today he didn't understand why the ships were operating without minesweeping protection.

Cmdr. Daniel J. Murphy Jr., captain of the Kidd, said in an interview that ''our capability to spot a moored mine is very poor.''

''The U.S. Navy, like all navies, is designed for deployment of integrated forces,'' he said. ''We have capability in detecting mines, both from helicopters and from minesweepers, but we don't have any of those things here.'' Asked why, he answered: ''I don't know.''

Pentagon officials said there was little doubt the mine that exploded Friday was planted by Iran, which has been at war with Iraq in the gulf region for nearly seven years. But until Iranian responsibility can be proved, one Pentagon source said, ''it will be hard to justify a retaliatory strike ... There's certainly nothing like that working now.''

The Bridgeton hit the mine off a fortified Iranian island and limped the 120 miles home with a hole in its port side.

Anthony Quainton, the U.S. ambassador to Kuwait, told journalists Friday, ''The damage will be inspected to see whether it can be repaired here in Kuwait.''

Bahrain's English-language newspaper Gulf Daily News quoted unidentified shipping sources as saying the mine that hit the Bridgeton was probably laid only two hours ahead of the blast.

The two new mines that were sighted were the first to be noted in about six weeks, said the salavage executives, who spoke on condition they not be identified. Mines have sporadically drifted down from the Iraq-Iran war zone at the northern tip of the gulf into the southern waters.

The three U.S. warships that had escorted the Bridgeton and a smaller reflagged vessel since Wednesday in their voyage up the gulf left the two tankers at the edge of Kuwait's territorial waters.

The destroyer USS Kidd, cruiser Fox and frigate Crommelin steamed south after spending the night off Kuwait. They were heading toward a Bahrain anchorage, where they were to tie up later today near the LaSalle, the headquarters' ship of the U.S. Mideast Task Force.

Kuwaiti patrol boats took charge of the 401,382-ton Bridgeton and the Gas Prince about 12 miles from the nearest Kuwaiti island and guided them to their berths.

The tankers were to have loaded cargo and sailed south next week, again with U.S. warships guarding them. It was not known if the damage to the Bridgeton would affect that itinerary.

No one was injured in the explosion, but the tanker took on water and listed for the rest of the trip.

The blast occurred as the vessel passed Farsiyah Island, which Iranian Revolutionary Guards use as a base for attacks on shipping. The Guards usually employ speedboats and fire at vessels with rocket-propelled grenades and machine guns.

Iran accuses Kuwait of receiving arms shipments for Iraq, whose ports were closed early in the war, and began regular attacks last September on ships owned by or trading with the emirate. Kuwait and neighboring Saudi Arabia also help Iraq export an estimated 300,000 barrels of oil a day.

According to Lloyd's Shipping Intelligence Unit in London, more than 330 ships have been attacked by Iran or Iraq since the war began in September 1980.

In Iran, a crowd of Iranians observing the Moslem sabbath in Tehran on Friday rejoiced at the news of the mine explosion, chanting ''Death to the USA 3/8'' and ''Persian Gulf of Iran, the Graveyard of Reagan 3/8''

Prime Minister Hussein Musavi said ''invisible hands'' planted the mine. His government has denounced the U.S. escort of reflagged Kuwaiti tankers and threatened to attack the convoys.

Musavi called the incident an ''irreparable blow to America's political and military prestige,'' according to Iran's official Islamic Republic News Agency, monitored in Cyprus.

The Bridgeton and Gas Prince are the first of 11 Kuwaiti vessels to be given U.S. registry and Navy escorts.

Pentagon sources said the next convoy would set out Aug. 6, passing as this one did through the narrow Strait of Hormuz at southern end of the Persian Gulf and steaming to Kuwait, Iraq's western neighbor on the northern shore.

Pentagon officials said privately that the mine apparently was moored to the seabed and positioned about 20 feet below the surface.

Diplomats and shipping officials have said Iran placed the Soviet-made mines that blew holes in four ships earlier this year near Kuwait's Al-Ahmadi oil port. Kuwaiti, U.S. and Saudi Arabian experts said last weekend they had cleared the last eight mines from that area, more than 40 miles north of the scene of Friday's blast.