A Cabinet minister said Friday a supertanker on fire off the northwest coast of Italy could cause "the most serious ecological disaster" ever in the Mediterranean if it spills its full cargo of crude oil.

Meanwhile, off the port of Leghorn, 90 miles southeast of Genoa, the port commandant said another "ecological disaster" was threatened by the Italian tanker Agip Abruzzo, which was rammed by an Italian ferry boat late Wednesday with the loss of 138 lives.Both ships have been ablaze since the catastrophes despite the efforts of scores of fire tenders and tugs pouring water and firefighting foam into them for the better part of two days.

In the sea about four miles off Genoa, the menace came from the 109,000-ton Cypriot tanker Haven, where an explosion Thursday started a colossal fire and almost broke the tanker in two.

Five crew members of the Haven, including the Greek skipper, died in the explosion and the 31 other crew members were rescued and taken to shore hospitals with burns, 11 of them in serious condition.

Twenty fire tenders and tugs and 13 fire extinguishing experts flown in from Britain by the ship's insurers were battling the flames on the burning ship and the sea around it. Port officials estimated that more than 7 million gallons of Iranian crude oil had gushed into the sea from one of its tanks.

The Haven had more than 40 million gallons of crude oil aboard when the explosion took place. It was listing badly and sinking slowly, and port officials said if it broke apart and sank it would almost certainly spill the rest of its crude oil.