Four ships have already left the James River in Virginia

The first of the 13 former World War II ships are due to arrive at Able UK, in Hartlepool, in about a week's time.

On Friday the Environment Agency said they were blocking the move, because planning permission for a dry dock, where the work would be carried out, has not been granted.

But Able UK said it is satisfied it has the relevant permission to carry out the work.

The US Maritime Administration said the ships must continue to cross the Atlantic while they work towards a resolution of the issues.

The Americans said they received official approval from the Agency before the first ships departed - and that the vessels would never have left their moorings in Virginia without it.

In a statement, the US Maritime Administration (MARAD) said: "[MARAD] is aware of issues raised in a recent statement released by the UK Environment Agency and remains committed to responsible ship disposal solutions involving partners in the United States and abroad.

"As we work toward a resolution of these issues between the UK Environment Agency and Able UK, the ships will continue to transit the Atlantic.

"Prior to the ships' departure, MARAD sought and received official approvals from the UK Environment Agency, the UK Maritime Coastguard Agency, the US Environmental Protection Agency and the US Coast Guard."

"Additionally, MARAD implemented all towing safety recommendations required by the insurance carrier, the oceangoing tug company, and an independent marine surveyor prior to the voyage."