Strong winds and rough seas are hampering efforts to tackle the ecological disaster in north-west Spain after a tanker laden with sticky fuel oil broke up and sank.

The giant oil spill from the Prestige has prompted urgent international calls for tighter controls on the movement of single-hulled oil tankers in coastal waters.

	'Prestige' Built: 1976 Weight: 42,000 tons Cargo: 77,000 tons of oil Owners: Mare Shipping Registered: Bahamas Vulnerable vessel

An armada of tugs and clean-up vessels from around Europe has approached the scene, about 210 kilometres (130 miles) off the Spanish coast, but huge waves have prevented them containing surface oil.

Winds are threatening to blow more oil ashore from the 26-year-old Bahamas-registered tanker, which split in two on Tuesday. Its hull had cracked during a storm last Wednesday.

Ecologists, soldiers and volunteers are racing to rescue tar-coated sea birds and clear the black sludge covering more than 80km (50 miles) of Galicia's coastline.

Dozens of inlets and coves are affected, from Cape Finisterre north to the city of La Coruna.

Finger of blame

The Spanish Prime Minister, Jose Maria Aznar, has vowed to make whoever is responsible pay for Spain's worst shipping disaster in 10 years.

	:	Sinking tanker
Pictures of the Prestige oil slick

Adding to the debate over who is to blame for the disaster, the Chief Executive of Smit Salvage, the Dutch company which tried to save the ship, has told the BBC that the ship should not have been moved.

Companies make money by hiding behind flags of convenience in the event of trouble

Andrew, UK

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"The structural damage was certainly not improved by the five days of towing into heavy seas... we would have been better off in a sheltered area, in which the damage would not have increased and we could have had much easier and rapid control of the vessel," Hans van Rooy said.

Experts ignored

However, he said that the decision rested with politicians rather than scientists.

"It became too much the art of politicians, and the proper debate on the damage and the safety and the possibilities never took place... we would have preferred to have a proper debate with experts, and not with politicians," Mr van Rooy added.

	Enlarge image

Single-hulled tankers are not due to be outlawed in Europe for another 13 years, but Spain has said it will push for the proposed European Union ban to be brought forward.

The French President, Jacques Chirac, called for "draconian measures" to prevent such shipping disasters.

"I am horrified by the inability of those in charge, politically, nationally and particularly at European level, to take action to stem the laxity which permits these ships fit only for the dustbin to carry on," he said.

Environmental impact

It remains unclear if the oil inside the Prestige will disperse if the ship breaks up further.

Environmentalists warn that if the entire cargo of some 70,000 metric tons spills, the resulting damage could be double that caused in the Exxon Valdez disaster off the coast of Alaska in 1989 - one of the worst ever.

Major oil spills

Jan 1993: 85,000 tons off the Shetland Islands Dec 1992: 80,000 tons near La Coruna port in Spain March 1989: 38,800 tons off Alaskan coast 1979: 160,000 tons off Tobago March 1967: 119,000 tons off the UK

Up to 4,000 tons spilled from the ship before it went down.

Lars Walder, of Smit Salvage, said: "It is hoped the majority of the oil has stayed within the vessel, but that part of the ocean is 3.5km deep and we must still wait and see what happens".

Experts say the low sea temperature may delay the seepage of oil from the compartments that split and might even solidify the cargo.

The Spanish authorities have suspended fishing along the 100-kilometre stretch of coastline from Roncudo to Cape Tourinan, and financial compensation has been promised to local fishermen.

Whole communities depend on fishing in the area, which is famous for its shellfish, octopus and crabs.

To the south, Portugal is bracing for the possibility that oil could foul its Atlantic beaches and rich fishing grounds.