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.”
GMB regional organiser Jeff Beck said: “We haven’t as yet had any confirmation of any closure but we can confirm we’re meeting with Ford tomorrow and a new agenda has been arranged, which we’re yet to see.
“If our worst fears are confirmed it will mean disaster for both our members in Bridgend and the community at large, who we will stand by the through thick and thin.
“The ironic part is, in the week that Donald Trump is meeting the UK Prime Minister and talking up a special relationship and trade deal with the UK and the US, if the plant does close the new line is likely to be taken to Mexico by an American company.
“So much for the special relationship, Mr Trump.”
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.
Rebecca Long-Bailey, shadow secretary for business, energy and industrial strategy said: “This is worrying news, first and foremost for Ford employees and their families who are left unsure as to their futures, but also for the jobs across the supply chain and the impact on the local economy in Bridgend.
“Hot off the heels from Honda, this would be another devastating blow to our car industry and to the UK’s wider manufacturing base.
“The Government must urgently meet with Ford to secure the plant’s future.”
The Bridgend plant has been under threat because of falling demand for the two engines it makes and lower projections for the Dragon engine it is scheduled to start making this year.
It has been manufacturing engines for 40 years.
Unions had expressed fears that 1,000 jobs at the factory could be lost if new contracts were not found.
The site opened in 1980 and covers an area of 60 acres.
Unions have previously warned of a ballot for strikes if compulsory redundancies are made.
The news is the latest blow to the UK’s car industry.
Honda has announced plans to shut its Swindon plant in 2021, while fellow Japanese carmaker Nissan reversed a decision to build its new X-Trail vehicle at its Sunderland plant.
Jaguar Land Rover, owned by India’s Tata Motors, is also cutting jobs.
Ford also has an engine plant in Dagenham, Essex, and a plant making transmissions in Halewood, Liverpool.