Union leaders have been called to a meeting with Ford bosses on Thursday amid fears the car giant is to close one of its UK plants.
Officials are worried about the future of the engine factory at Bridgend in South Wales.
The site employs 1,500 workers but supports many more in supply firms.
Ford refused to comment on the speculation.
A Unite spokesperson said: “Unite will be meeting Ford first thing tomorrow morning and will comment further once the details of any announcement are known.
“Our priority is our members’ jobs, the communities and livelihoods in the supply chain that Ford Bridgend supports.”
Ford announced last month it was cutting 7,000 white collar jobs worldwide, with up to 550 expected in the UK.
The US manufacturer said the cuts represented 10% of its global salaried workforce and 20% of its management positions.