About 300 Maldive Islands pirates attacked an American-owned oceanographic survey ship in the Indian Ocean, looting the vessel and kidnaping at least one crew member, radio reports from the ship said yesterday.

The vessel, the Alysse Maru, reportedly was heading for the U.S. Navy facility on the island of Diego Garcia. Seven of the 10-man crew were aboard, but there was no word on the fate of three others, including the captain, who were left behind.

In Washington, the Pentagon said the ship was leased by Jacques Cousteau, the underwater explorer. But in France, Cousteau said, "I know nothing about this. We have absolutely nothing to do with that ship."

Distress calls from the ship were picked up by ham radio operators in Kenya, Australia, South Africa, Israel and Rhodesia, according to Bruce Johnson, assistant secretary of th International Amateur Radio Union based in Connecticut. Jonnson, who was visiting East Africa, and other ham operators gave this account:

On Saturday, the Alysse Maru developed engine trouble near the Maldivian capital of Male. The crew was removing a piston from the engine when a Maldivian vessel approached and offered help.

Once the ship was towed to calmer waters, 300 islanders carrying machetes and handguns swarmed aboard and locked the crew in the pilot house. The pirates then took about $60,000 worth of equipment and supplies.

There are conflicting accounts of what happened next, but apparently one crewman was kidnaped, and two others went to look for him.

Still missing when the ship sailed were the captain, Kenneth Leonard, chief engineer Craig Williams and the medical officer, Thomas Wiemken.

The ham radio operators notified the U.S. government and the Navy sent a reconnaissance plane from Diego Garcia. The aircraft dropped food and medicine to the crew and began escorting the ship.

The radio amateurs gave the names of the seven crew members remaining on the ship as Kyomi Oda of Japan and six Americans: Frederick Neil Lockard, Oscar Leroy Hromatka, Nicholas Ogburn Laney, Gary Blumenthal, Gary Milton Ruehle, the radio officer, and his son, John Arthur Ruehle, 13, cabin boy. The younger Ruehle reportedly suffered a blow to the head during the takeover. His condition was not known.

The Maldives, a longtime British protectorate that became independent in 1968, are a 500-mile-long chain of small, low-lying coral islands. The islanders have been famous sailors for centuries. In modern times they have acquired a more notorious reputation as pirates, usually preying on private yachts.

After a ship ran aground, the pirates would invite it to take refuge in a nearby harbor and invite the crew ashore. Then they would declare the ship abandoned and claim it for salvage. A number of cases of this nature were reported to the U.S. Embassy in Sri Lanka several years ago.

A number of mariners who passed through the Maldives in recent years have complained that the islanders lured their yachts onto the coral reefs that surround many of the islands, usually by removing warning markers.