Train-making company Bombardier is set to announce big job losses at its UK plant after losing out on a lucrative new-carriage order.
Bombardier has called a media briefing for Tuesday morning at which it is feared it will announce up to 2,000 job losses among its 3,000-strong workforce in Derby.
A consortium led by Bombardier had been competing with a consortium led by Siemens of Germany for a contract for 1,200 new carriages as part of a £6 billion upgrade of the Thameslink rail route.
Last month the Government announced that Siemens would be the preferred bidder for the contract for Thameslink, which runs from Bedford to Brighton.
Announcing the winner, Rail Minister Theresa Villiers said the bid by Siemens, who will build the new carriages in Germany, represented the "best value for money for taxpayers" and stressed that the contract would create up to 2,000 new UK jobs.
However, it was vital for Bombardier's future that it won the Thameslink contract as most of its other contracts are due to finish in September this year.
The Unite union described the Government's Thameslink decision as "a hammer blow for Derby and British manufacturing", while TUC deputy general secretary Frances O'Grady said it was a "devastating blow for Bombardier, Derby and the wider UK economy".
Bob Crow, general secretary of the RMT union, said: "No one should underestimate the devastating consequences of the Government sending the Thameslink fleet contract to Germany.
"Thousands of skilled workers are now under threat of ending up on the dole as a result of this grievous hammer blow to train building in the UK."
He went on: "This act of political sabotage to a key element of the remaining UK manufacturing base could leave the nation that gave the world the railways building nothing but a few basic components. RMT will continue to work with politicians, the workforce and local communities to fight this industrial vandalism that would reduce UK train building to nothing but rubble."