Hundreds of jobs could go at a steelmaking factory in Newport after its owner announced it was shutting part of its operations.
The steel giant Tata is closing its Orb Electrical Steels base in the Pill area of the city.
Up to 380 jobs could go from the plant, which makes electrical steel used in power transmission for vehicles.
The company has been for sale since May 2018 as Tata had decided to concentrate on its core steel production business.
Tata Steels European operations head Henrik Adam said: “I recognise how difficult this news will be for all those affected and we will work very hard to support them.”
BBC Wales understands that the 380 workers can be redeployed.
Unions said Tata – which employs nearly 6,000 workers in Wales – was breaking its commitments over job guarantees.
Orb Electrical Steels is part of Tata’s Cogent division, part of which is being sold to the Japanese steel company JFE Shoji Trade Corporation.
There has been steelmaking on the site since 1898.
However Mr Adam said the Orb site had been loss-making for several years and had struggled to compete as customer requirements had outstripped the site’s capabilities.
Converting the site would have cost in excess of £50m, he added.
“Continuing to fund substantial losses at Orb Electrical Steels is not sustainable at a time when the European steel industry is facing considerable challenges,” Mr Adam said.
“Today’s proposal will be sad news for our colleagues at Orb.”
Roy Rickhuss of the Community steelworkers’ union called it “shocking” news which “makes a mockery of the understanding we reached with Tata around the jobs guarantee”.
“There has been no consultation about this proposal either at UK or European level and company management should hang their heads in shame in the way this has come about,” he said.
“This is of course extremely devastating news for workers at the Orb, but all Tata Steel workers should be concerned by the way Tata is breaking its commitments.”
He called for government intervention.
Mr Adam said workers would be offered alternative employment at other Tata sites where possible and consultations with staff and unions would start shortly.
Tata is also closing its Wolverhampton Engineering Steels service centre, with up to 26 jobs at risk.
Analysis by Brian Meechan, BBC Wales business correspondent
There have been concerns for the future of Tata’s Cogent operation for a few months, ever since it was put up for sale.
Cogent had been put up for sale by Tata in May last year after the Indian owners had decided to concentrate on its core steel production business, as it planned to merge with the German company Thyssenkrupp.
Given Cogent’s specialism, it was hoped that a buyer could be found, but unions said at the time they were not persuaded by the case for a sale.
They had privately been growing increasingly concerned about the future of the plant. This decision could set Tata and the unions on an even bigger collision course.
As part of the unions’ agreement to support less generous pensions, they believe Tata committed to no compulsory redundancies until 2026.
Tata has always maintained that it committed to try to avoid compulsory redundancies.
Unions could see this as breaching a commitment to its entire Welsh workforce, and industrial action could be possible, they say.
Newport East MP Jessica Morden said job losses would be “devastating news” for the highly skilled workforce and families.
“What is particularly tragic is that this the only UK plant with the potential to produce electric steels for motors and with investment, vision and government backing this could be the key part of the supply chain for electric vehicles.”
She added: “We have called for an industrial strategy and this shows why we need it. This is a strategically important business that could be underpinning the UK automotive industry and so I will be contacting UK and Welsh government ministers urging them to do all they can to help.”