A top executive of car giant General Motors is being quizzed for assurances about jobs at Vauxhall factories in the UK.
Leaders of Unite will join business secretary Lord Mandelson in talks with Nick Reilly, the US firm's head of operations in Europe.
The meetings will be the first chance unions and the Government will have to ask detailed questions to GM over its future plans since the car maker decided not to sell its European operations, including Vauxhall.
Mr Reilly will be pressed about GM's long-term plans for the Luton and Ellesmere Port plants, which employ thousands of workers.
He has said that decisions about the future of plants across Europe should be taken by next month.
The Government has said it will consider offering financial support to help secure the future of Vauxhall.
Unite's joint leader, Tony Woodley, will seek assurances over the future of Vauxhall's 5,500 UK workers, although some job losses are expected as GM moves to cut costs.
GM had struck a deal with Canadian car parts maker Magna to sell its European business, which was set to cost hundreds of jobs in the UK.
The German government had pledged to give Magna three billion euros in loan guarantees to help secure German factories. But GM suddenly cancelled the sale earlier this month in the face of an "improving business environment" for the firm.
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