Steelmaker Corus is set to cut 3,500 jobs worldwide, including more than 2,500 in the UK, the BBC understands.
Corus said it could not comment on rumour or speculation, but the company, like all steelmakers, is facing an unprecedented downturn in demand.
One union official told the BBC Corus would announce its restructuring plans to workers at 0930 GMT on Monday.
Corus, a subsidiary of India's Tata Steel, employs 24,000 people in the UK and 42,000 worldwide.
According to the Sunday Times, the Anglo-Dutch steelmaker is not planning to close any of its British plants.
Corus's main UK sites are at Port Talbot, Scunthorpe and Teesside. It also has a site in Rotherham.