Former staff of a County Durham company who were involved in the new Wembley Stadium project have lost their jobs.
Assurances have been given the project will continue on schedule
Last month, a deal was struck to transfer workers from Darlington-based Cleveland Bridge to a new firm when the County Durham company quit the project.
Now their new employer Hollandia/Fast Track has cancelled the contracts of 200 on-site steel workers.
Unions said they were shocked at the development and criticised the decision to sack the workers.
In a statement, the Wembley project's main contractor Multiplex said: "Multiplex has been advised that the decision by Hollandia/Fast Track resulted from independent action taken by the on-site steel workers, who had made unacceptable additional demands despite agreeing new employment contracts with Fast Track in July."
It added: "Hollandia and Fast Track advised Multiplex that in breaching the new contractual agreement, the workers left them in an untenable position with absolutely no option but to end their employment."
Multiplex said it had obtained assurances from Hollandia that the project would continue on schedule .
Jimmy Skivington of the GMB union said he had been contacted by a number of the affected workers and rejected claims the workers' demands were unacceptable.
He said the situation followed negotiations this week about redundancy selection.
He said: "To sack the workers is absolutely incredible as far as I am concerned.
"You can disagree, but don't go and sack the workers on that basis. All they are looking for is a fairer redundancy selection.
"A lot of them are finding it hard to come to terms with."