The cargo holds of an oil tanker that sank off the Italian coast apparently are empty and the danger of an "ecological catastrophe" for the Mediterranean seems to be over, a senior maritime official said.

Adm. Antonio Alati, commandant of the Genoa Port Authority who is in charge of coordinating operations to contain the oil spill, said Tuesday an examination of the hull of the Haven by a navy mini-submarine showed that the hatches of its tanks were open, indicating they are empty.The admiral said most of the approximately 42 million gallons of Iranian crude oil aboard the Haven when an explosion set fire to it last Thursday must have either burned or been solidified in the tanks during the three-day blaze before the vessel sank Sunday.

"Altogether about 10,000 (tons) to 12,000 tons of oil (between about 2.9 million and 3.5 million gallons) is believed to have been spilled into the sea, half of which has already been cleaned up by the anti-pollution ships," he said. "At this point the potential for an ecological catastrophe appears to be ended."

But a technician aboard the specialist ship Ragno, which is using underwater television and other sophisticated equipment to examine the Haven on the sea bottom, warned that until divers or television cameras can get inside the ship, nobody could be certain of the amount of oil remaining in its tanks.

The 109,000-ton Cypriot tanker Haven sank some 2 miles off Arenzano, 12 miles west of Genoa, Sunday, three days after an explosion that set fire to the ship and spilled an estimated 11 million gallons of its 41 million-gallon cargo of Iranian crude oil into the sea.

Most of the officials heading the operation to clean up huge oil slicks from the surface believed at least 28.7 million gallons of oil wereaboard the Haven when it sank.

They feared that if the ship broke up and released its oil, it would cause the greatest "ecological disaster" ever to hit the Mediterranean. But the Haven settled gently in 200 feet of water on to a sandbank over which it had been towed by salvage tugs.

The port authority statement confirmed that divers who inspected the tanker late Monday reported oil leaks from the wreck were minimal.