Seven years ago Bill Clinton ruled that the US navy's "ghost fleet" of 120 decomposing hulks could not be scrapped in developing countries because their pollution and toxic loads risked the lives of shipyard workers.

But a British company has signed a $17m (£10.8m) contract to dismantle the most fragile vessels at a dockyard near Hartlepool.

AbleUK, which also stands to get two almost-complete oil tankers from the US government as part of the deal, is expected to submit detailed plans of the proposed voyage in the next few days.

Under the contract, a copy of which has been seen by the Guardian, the company is obliged to remove all 13 ships from the James river in Virginia, where they have been slowly rusting for the past 15 years, by the end of November or face a $1,350 daily fine for each vessel.

They are in such poor condition that to stand any chance of surviving the crossing, they will have to leave by the end of this month, before the onset of autumn storms in the Atlantic.

A leading US salvage expert, who has surveyed most of the ships involved in the contract, has told the Guardian that there is a risk that some of the ships will be breaking up by the time they reach Teesside.

Tim Mullane, of Virginia-based company Dominion Maritime, said: "They're leaking, and listing, and that's just sitting at anchor in a river. If they get to sea, some will definitely start to break up.

"A pollution slick will follow them all the way across the Atlantic. When they get to Teesside they will be leaking even more and be more liable to break up. Their bottoms are rotting out and they will leak at anchor.

"Some of them have hundreds of tonnes of heavy oil aboard which will leak out and pollute the river there."

At least two ships would struggle to make it 15 miles into the Atlantic, he added.

Some of the vessels are almost 60 years old. The 12,000-tonne supply ship Canisteo was launched in July 1945. Over the next 50 years the Can-o-shit, as she was known to her crew, was involved in the Cuban missile crisis and the Korean war.

Last night environmental campaigners condemned the deal. Friends of the Earth claimed that the AbleUK dockyard would not be fully operational and that no planning permission had been granted by the local authority. "The fear is that the boats will come over and have to wait in the river Tees in an even more dangerous state," a spokesman said.

The Irish government and the Scottish executive have also voiced concern about the pollution threat posed by the fleet as it passes through their coastal waters. The safety risks means they will not be allowed to go through the English Channel, one of the world's busiest shipping lanes, and will instead go around the northern tip of Scotland and down the North sea.

The deal may yet be scuppered. The Department of Transport's maritime and coastguard agency said it had asked for a full pollution risk assessments of these ships, a detailed passage plan showing exactly where they would go and what they would do in bad weather, and what alternatives they have in an emergency.

"We have the power to refuse them on safety grounds," a spokeswoman said.

But AbleUK moved to calm fears that the ships would pollute Teesside, insisting that it would be able to handle all 13 vessels at the same time.

"Once within the facility the basin will be drained and sealed - allowing 'dry' dismantling which, as well as being much safer for those undertaking the work, will prevent any risk of wastes from the vessels entering surrounding waters," it said on its website.

The environment agency also defended its decision to approve the deal.

"There is free trade in waste for recovery under international and EU law," a spokesman said. "To obstruct it without valid reason would put the UK in breach of that law."

In a letter to FoE's lawyer, the health and safety executive said it was legal and acceptable for asbestos to be imported into the country because of the high standards expected of AbleUK.

It also said there was no capacity in US shipyards to dispose of such polluting materials.

Robyn Boerstling, of the US maritime administration, said: "These ships are desperately in need of disposal, and a commercial decision has been made that AbleUK on Teesside offers the best option. They have to be removed due to the toxic substances control legalisation."

On Teesside, reaction to the fleet's imminent arrival was mixed. "Most people are delighted that much-needed work is coming but they do not necessarily like the idea of taking US waste," said Carol Zagrovic, a local community worker.

"When locals ask for information they're only told that it is an opportunity, or that it means work. But a lot of people are horrified, too."