Union leaders are calling for the creation of a joint task force to secure the long-term future of the country’s biggest rail assembly plant amid fears of huge job losses.
Alstom is consulting on potential redundancies - around 550 at its train manufacturing site in Derby, with 780 contractors also at risk.
The union's general secretary Sharon Graham said: "There is absolutely no justification for the proposed job losses.
"It is madness that there is a huge amount of work that Alstom could and should be bidding for but the Government has not got around to tendering for it.
"The Government and Alstom should both be bending over backwards to keep hold of these highly skilled workers and this strategically vital and unique site.
"Unite will leave no stone unturned in its campaign to secure these jobs."
Unite said it believes a task force involving the Government, Alstom, the local council and the union is essential to develop solutions to prevent the job losses occurring or at worst mitigating the numbers involved.
A combination of contracts being brought forward to the tender stage to allow Alstom to bid for them, combined with the company investing in the site and transferring in some of its overseas work, would end the need for job cuts and 'future-proof' the plant, said Unite.
The union’s regional secretary for the East Midlands Paresh Patel said: "Rail workers in Derby deserve better than this, their futures have been thrown into jeopardy by issues beyond their control.
"Ministers can’t be allowed to wash their hands of this crisis and they must come forward with a just solution.
"Equally, Alstom needs to play its part and invest in the site to reinforce its position as a world leader in train manufacturing."
A spokesperson for the Department for Transport said: "Rail manufacturing is an important part of the UK economy and we will work closely with Alstom as it continues to deliver its contractual commitments, as we do with all rolling-stock manufacturers.
"While this is a commercial matter for the company, we have already set up a dedicated cross-government task force to properly support workers at Alstom during what will be a concerning time."
An Alstom spokesperson said: "Alstom UK has been working with Government for the last six months with the joint objective of securing a sustainable future for our rolling stock factory at Derby Litchurch Lane, which has no confirmed workload beyond the first quarter of 2024.
"No committed way forward has yet been found and therefore it is with deep regret that we must now begin to plan for a significant reduction in activity at Derby by entering a period of collective consultation on potential redundancies at Litchurch Lane.
"We will fully support our dedicated colleagues during this exceptionally difficult time.
"The UK remains one of Alstom’s most important global markets and we will continue to operate 36 sites throughout the country across our rolling stock, services, and digital and integrated systems businesses.
"We look forward to fulfilling our commitments on HS2 and successfully competing for rolling stock opportunities across the UK in the future.
"We remain open-minded as to the future of non-production functions located at Litchurch Lane and to potential future alternative uses for the Derby site.
"We will begin an extensive review of options, and will fully involve our stakeholders in this process."
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