Just a few months after Vauxhall workers were celebrating the news they had secured the build of the new Astra, the car company is stopping production for a week at its Ellesmere Port and Luton plants because of falling European car sales.
In a statement reported by the BBC, the company said the move would "avoid building up stock".
John Fetherston, of union Unite, said: "Workers are not shocked, they know it is related to the downturn in Europe. Other car-makers are also affected."
Workers at the plants will continue to be paid during the shutdown, which starts on September 24.
Assembly of the next generation Astra at Ellesmere Port is scheduled to start in 2015.
Fetherston added: "Workers are confident in the future of the plant."
In May the threat of closure of Ellesmere Port was lifted when General Motors (GM) said it would invest £125 million in the factory and spend about £1bn in the UK component sector. It means the car factory will build at least 160,000 Astra cars a year.