MANAMA, BAHRAIN, DEC. 22 -- Iraqi jet fighters on a rare long-distance raid today bombed and set ablaze four supertankers used for storage at Iran's Larak Island oil terminal in the Strait of Hormuz.

One of the tankers, the 564,739-ton Seawise Giant, is the world's largest.

Within hours, Iranian gunboats set out in the dark and attacked the Swedish supertanker Stena Concordia with machine-gun fire in the southern Persian Gulf, maritime salvage executives reported.

Iran, meanwhile, claimed that its forces killed or wounded 1,000 more Iraqis who tried to retake a strip of Iranian territory that the Tehran government said its forces had regained from Iraq on Monday. Iraq denied Iran's claim.

The shipping executives, who spoke on condition they not be identified, said the 273,616-ton Stena Concordia was not damaged in the Iranian attack and there were no injuries among its crew. There was no immediate word on the ship's destination. The ship had been attacked by Iranian gunboats in June.

Twenty-three tankers or freighters have been hit this month by the two warring sides of the Iran-Iraq "tanker war."

Iran retaliates for Iraqi strikes on a ship-for-ship basis, picking targets from among neutral tankers and freighters plying the southern gulf.

Iraqi pilots seldom hit the Larak and Sirri Island terminals because their jets must refuel in-flight to cover the distance to the Strait of Hormuz. All ships entering or leaving the gulf have to pass through the Strait of Hormuz. The two nations have been at war since September 1980.

Besides the Seawise Giant, the other "mother ships" hit Tuesday were identified by shipping executives and by Lloyd's Shipping Intelligence Unit of London as the 392,985-ton Cypriot-flag White Rose, the 411,508-ton Liberian-flag World Petrobras and the 457,927-ton Burmah Enterprise, a British-flag vessel.

The executives said three tankers sustained heavy damage and that there were casualties, but they did not know how many.