LONDON -- A fleet of 13 decrepit and polluted U.S. ships due to sail for a British scrapyard will pass through the English Channel -- one of the world's busiest shipping lanes -- the demolition firm involved said.

The dilapidated navy supply ships, part of the so-called U.S. "ghost fleet", are polluted with asbestos, toxic polychlorinated biphenyls (PCBs) -- banned in the 1970s -- and varying quantities of heavy marine diesel oil.

Peter Stephenson, managing director of Able UK, awarded the U.S. Maritime Administration contract to scrap the vessels in late July, told Reuters the ships would pass through the Channel on their way to a special dock in Teesside, northeast England.

"The route plan is the southerly route -- through the English Channel," he said.

The prospect of the rusting hulks mingling with heavy traffic in the Channel has raised eyebrows, although the route has yet to be approved by British authorities.

It was widely believed that because of the size and instability of the hulks, some of which served in the Korean War, they would be towed across the Atlantic and then round the tip of Scotland.

But Stephenson said the route had been chosen by marine experts and advisers who were the best in the business.

Britain's Maritime and Coastguard agency (MCA) said French maritime authorities would need to be contacted because the passage plan would affect their coastline too. The MCA did not immediately know whether France could veto the plan. **** Environmental Risks****

Some of the ships, which have been laid up and rotting for years as U.S. officials argued over what to do with them, will set off from their anchorage points on the James River in Virginia in the next month.

Environmental groups have called the scheme an unacceptable risk.

"Apart from the obvious hazards, you are exporting toxic waste around the globe and we are worried this could set a precedent," said Greenpeace toxicologist, Mark Strutt.

Mike Childs, Friends of the Earth campaigns director, said Teesside was being wrongly cast as a "dumping ground for the rest of the world".

But Stephenson said the environmental risk posed by the ships was small.

"The facts are that there are no cargoes in them whatsoever," he said, adding that the quantity of asbestos per ship was no more than 100 tons.

Stephenson said banned liquid PCBs would be drained before departure leaving only "fixed" PCBs which were "not a risk".

Contrary to reports from "scaremongers" he said the vessels would carry very little oil, adding the ships had been carefully vetted for their seaworthiness by British and U.S. surveyors.

Nevertheless, the MCA said it was premature for the firm to talk of bringing the vessels to the UK before the plan had been authorized. "We need to see that there is absolutely zero risk to the environment by the importer," said MCA spokesman Mark Clarke. Clarke said a meeting involving the MCA, a representative for the Secretary of State for Transport and the British firm had been held on Wednesday to discuss the issue.

A decision would be made in days.