BBC News Online takes a look at what measures are in place in the UK to avoid such scenarios, with some environmentalists saying much more needs to be done.

In Britain, strict measures allow inspectors to prevent any ships from entering ports if there are fears over their safety.

But there are concerns - from both pressure groups and world leaders - that more needs to be done to avoid another oil disaster at sea.

The stricken Prestige had not visited a European port for more than two years before it sank off the Spanish coast.

Britain's Maritime and Coastguard Agency (MCA) can detain suspect ships in port and refuse to release them until any faults are corrected.

There is plenty of opportunity for this to happen again

Friends of the Earth

Of the 7,000 ships that visit UK shores each year, about 160 are detained.

The Prestige was detained briefly when it docked in Rotterdam in September 1999, but any faults found were fixed and it was declared seaworthy before its departure.

The MCA - an agency of the Department for Transport, Local Government and the Regions - also takes action against pollution from shipping and offshore installations.

It brought six successful prosecutions for oil pollution offences at sea in 2000, with fines imposed totalling �86,000.

It has its own national contingency plan for dealing with large-scale environmental disasters.

'Learning experience

The MCA is sending out two experts to observe the unfolding disaster off the Spanish coast and has offered help with the clean-up operation.

MCA spokesman Mark Clark said: "Any spill anywhere is a learning experience for us all.

The Prestige sinking has caused ecological disaster

"Our team will be looking at the management of command and control of the incident."

A spokesman for Friends of the Earth said there was a clear risk of a disaster like the Prestige spillage happening off the coast of Britain.

A prime example of this was the 1996 Sea Empress oil spill off the Pembrokeshire coast in Wales, he said.

"Single hull tankers can still sail around UK coastlines, so there is plenty of opportunity for this to happen again."

Out-dated

The pressure group was concerned that oil-carrying vessels were not always properly inspected, with less rigorous standards in some parts of the world.

It also wants better controls on the ownership of ships and the oil they transport, to avoid confusion over liability for spillages.

Single hulled tankers like the Prestige are said to be out-dated and lacking the protection of a second hull, seen on more modern vessels.

They will be outlawed from European waters by 2015, and are being phased out already to be replaced by twin-hulled ships.

But it will be a long process, with Lloyds Marine Intelligence estimating that 52% of tankers of more than 10,000 tons currently in operation are single-hulled.