Ford is to cut 25 full days of production between 1 February and 30 April at its Dagenham plant in Essex.
The cutbacks, blamed on weak export markets for the Fiesta in Europe and South and Latin America, will hit 3,500 workers and see around 40,000 less vehicles produced in the first quarter.
Dagenham, which is already operating a four-day week, exports around 45% of its 250,000 vehicle output. The plant mostly produces Fiesta cars and vans, plus a few thousand Mazda 121 saloons.
A Ford spokesman said: ‘There will be no job losses. Workers will be used for non-production activities and training.’
This would happen in the run-up to Easter and continue afterwards. Ford has yet to decide whether to close the plant at Easter.
The Ford Fiesta was the UK’s biggest selling new car in 1998, with sales of 116,110.
Rover, meanwhile, is to close its Bargoed factory in south Wales with the loss of 45 jobs. The company is in talks with unions. The factory produces components for the discontinued Rover 100.