On Friday, Britain's Environment Agency withdrew permission for the rusting chemical vessels to be dumped in a scrapyard in England.

But the crumbling fleet is refusing to turn around and return to America and is just days off the coast of Ireland.

The agency announced that the waste management licence granted to Able UK is invalid, which means the ships cannot legally be dismantled on Teeside.

But the ships are defiantly continuing the last leg of their journey, with two believed to be only five days from the Irish coast.

Green Party leader Trevor Sargent said the four toxic ships must return to America immediately.

He said: "Britain has decided it dooesn't want these toxic vessels in its waters and the Irish Government must make a strong stance against them also.

"These vessels should never have been given a licence to be scrapped in Britain in the first place.

"Now they must return to the U.S. where two companies are willing safely to dismantle them.

"They are giving the lame excuse that they can't travel back to the U. S. because they have not enough fuel in the tugs to make the return trip across the Atlantic - but that can be easily solved.

"It is very important that the Irish Government make these ships return to the U.S. and put an end to toxic tourism."

Friends of the Earth's Executive Director Tony Juniper said: "The Environment Agency must now make it clear that the ships must not be allowed to enter UK waters and must send them back to the United States.

"We are delighted that the agency has realised it exists to protect the environment rather than help America get rid of its waste overseas.

"This is a real victory for the environment and for local people on Teesside. We are now calling on the British Government to make the ships turn around and return to America."

The EA said it was concerned planning and environmental requirements for dry dock dismantling, which it considers safer, had not been met.

It said if they are met it will give the go-ahead for the scrapping but if the ships can't be dismantled without threatening the environment, regulations provide for the waste to be returned to the country of origin.

Able UK managing director Peter Stephenson said: "We are confident we will have relevant planning permission in place for recycling and the creation of dry dock facilities by mid-November."

Friends of the Earth have made the US Government, the Coastguard and Hartlepool Borough Council aware that the ships do not have legal permission to be scrapped in Hartlepool and must be sent back to America.

The ships contain more than 500,000 gallons of fuel and oil, and have been classified as having a high potential to leak by the US Marine Administration.