The firms are understood to have pulled out because of mounting concern about the buildability of the complex cable-stayed design of the bridge.

Concerns about construction risks on the job centre on the two independent curving bridge pylons. They will have to be built as huge unconnected post-tensioned structures rising 180m and 140m into the air.

Now just Northern Ireland’s Graham Construction and Vinci remain in the bidding.

A source told the Enquirer: “There have been concerns for some time about the estimated price and buildability of the bridge.

“It looks like the contractors have looked at the complexity of the structure and decided that the risks are too high.”

But Sunderland Council said it was confident that it was still on track to deliver the landmark bridge across the Wear with two bidders on board.

Councillor Paul Watson, Leader of Sunderland City Council, said: “Submitting a bid of this scale is not something international construction companies enter into lightly.

“Market forces determine that these companies must align their resources with the projects available to them.

“With two internationally-acclaimed contractors in the bidding process, Sunderland City Council is confident that it can deliver a landmark, affordable, and much needed new bridge across the Wear.

“As was demonstrated on the ‘Best and Final Bid’ submitted to DfT – the Project represents a very high return for the taxpayer, at a public value of £4 generated for every £1 spent.”

“The New Wear Crossing forms part of the Sunderland Strategic Transport Corridor (SSTC) that will open up significant development and investment opportunities, creating jobs and growth in Sunderland and the north east region.

“It will provide much needed connectivity between key city locations, including the North East’s Low Carbon Enterprise Zone, major assets including the Port of Sunderland and the dynamic Nissan car plant.

“In addition the project will further demonstrate Sunderland’s bold approach to economic regeneration.

“It will unlock private sector investment and acres of brownfield regeneration land for employment, housing and UK-based manufacturing.”