A French supertanker set ablaze in a mystery explosion which the operators said was caused by an attack trashed about in distress off the Yemeni coast late yesterday.

The explosion which left the supertanker, which is chartered by Malaysian national oil company Petronas, badly holed came a week before the second anniversary of a terrorist attack in Yemen on the destroyer USS Cole.

While a French diplomat in Sanaa said the blast was caused by a small boat packed with explosives that rammed the tanker, the French foreign ministry said there was no evidence so far of an attack.

Yemeni authorities, meanwhile, set up a crisis cell and voiced fears of a major oil slick spreading along the Arabian Sea coast.

"The oil tanker was rammed by a small boat stuffed with explosives," as it came by an offshore terminal some 700 kilometres east of Aden, Vice Consul Marcel Goncalves told AFP .

"It seems to be an attack in the same style as the USS Cole," he said of the hi-tech destroyer bombed by suspected al-Qaeda militants in Aden harbour on Oct 12, 2000.

Seventeen US sailors died and 38 were wounded in that attack.