BMW will shut down its Cowley Mini plant for almost a month, in a move blamed on the credit crunch.

Production lines at the BMW-owned factory, which employs more than 4,500 people, will shut down on Sunday, December 7, until Monday, January 5.

This is 11 days longer than had been expected.

The closure is in addition to a weekend shutdown between November 21-23.

But bosses have brought forward part of an annual bonus windfall, normally paid in January. Workers will now receive a £400 cash payment in December to help offset the cost of Christmas.

The announcement of the prolonged break follows BMW Group’s 2008 results for the third quarter. These show that pre-tax profits for the Munich-based multinational car producer have tumbled 63.5 per cent, from £616.1m in July, August and September last year to £224.7m in the same three months this year.

Oliver Zipse, managing director of the Mini plant, said: “Mini continues to weather the current economic conditions reasonably well.

“Worldwide sales are currently 12.1 per cent up this year and production remains at about the same level as last year.

“Due to our flexible working time arrangements with working time accounts, our associates will receive their basic pay during this period. Also, in recognition of their hard work during this challenging year, we have decided to bring forward a part payment of the annual bonus.”

BMW spokesman Angela Stangroom said: “Mini figures show that for the three months in 2008 we actually sold more Minis than last year — up 1.4 per cent from 57,315 to 58,105.

“And the fact that production is at about the same level as last year is indicative of the strength of the brand.”

She added that workers would have to “pay” back the hours they owed the company during the new year, but there were no plans for any job losses.

The plant operates a Working Time Account where workers “bank” their overtime which they can take back or the system can work in reverse and they have to work for the hours lost.

Ms Stangroom added: “The flexible working time arrangements are able to deal precisely with these type of fluctuations. There will be a position going into the new year where those hours will be taken back over a period of time.”

Bernard Moss, union conveyor at the plant, said: “Everyone was expecting an announcement like this so I think most people are simply relieved to know where they stand now in the run-up to Christmas.”

“So far, there are no shift changes planned. But things can change from week to week. It’s just fingers crossed for the new year now — though to be honest I would be quite pleased if production figures next year were similar to this year’s.”

For the first nine months of this year Mini production was up 12.1 per cent, from 164,891 in 2007 to 184,915. BMW Group sales were also up slightly at £32,630m compared to £32,623 in 2007. Management expects the Cowley plant to produce about 237,000 cars this year — the same as last year.