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Meanwhile, a no-fishing zone around the coast has been extended to cover a much wider area.

The BBC's Claire Marshall says that the ban will only increase the misery being suffered by fishing communities of the Galician region.

Earlier, European Union Transport Commissioner Loyola de Palacio called on EU member states to take urgent steps to ban the use of single-hulled tankers in European waters.

Though most of the oil appears to be still trapped in the ship, at least 80 kilometres (50 miles) of the Spanish coastline have already been blackened by oil since the Prestige ran into trouble during a storm last week.

The Spanish authorities are erecting more floating booms around the areas which they fear could be worst hit.

'Old and out of date'

Ms de Palacio was speaking in a debate in the European Parliament, prompted by the sinking of the Prestige, which had 77,000 metric tons of oil on board.

Sale of shellfish has been banned in many areas

"If heavy fuel is being transported, then double-hulled tankers have to be used, because the last accidents implicated single-hulled tankers that were old and out of date and were carrying heavy crude oil," she said.

She called for a decision to be taken outlawing single-hulled tankers at a forthcoming meeting of EU transport ministers in Brussels.

Spanish Prime Minister Jose Maria Aznar also called for measures to improve safety and a European compensation fund for similar disasters.

Fishing woes

The EU agreed in 2000 to ban single-hulled tankers by 2015, and to set age limits for tankers using the territorial waters of EU states.

	:	Sinking tanker
Pictures of the Prestige oil slick

On Thursday the Danish Government, which currently holds the EU's rotating presidency, backed an earlier call by Ms de Palacio for these measures to be implemented ahead of schedule.

A satellite image shows the slick spreading from the wreck (l) to the coast on 17 November
	'Prestige' Built: 1976 Weight: 42,000 tons Cargo: 77,000 tons of oil Owners: Mare Shipping Registered: Bahamas Vulnerable vessel

Correspondents say 3,000 fishermen have been directly affected by the pollution, while others are hurrying to bring in their harvest before more oil hits the coast.

People are now unable to fish along more than 300 km of coastline, and the sale of shellfish has been banned in many areas.

Spanish officials say at least 40 beaches have so far been affected.

Up to seven more oil slicks are said to be out at sea, one of them eight kilometres (5 miles) long.

The Prestige finally sank after breaking in two on Tuesday.

Salvage workers believe it is the tanker's own fuel that has leaked into the ocean, rather than its cargo.

Environmentalists warn that if the entire cargo spills, the resulting damage could be double that caused by the Exxon Valdez in Alaska in 1989 - one of the worst ever.