Magna, the company which is planning to buy a 55% stake in Vauxhall owner GM Europe, is believed to be planning to cut 1,830 jobs at Vauxhall plants in the UK.

1,000 jobs will be threatened when the Luton plant's current van building contract expires in 2013, while 830 jobs are under more immediate threat at Ellesmere Port - the home of the new Astra.

Unite's joint general secretary, Tony Woodley, said: "The job losses are right across the company.

"The truth of the Magna deal is unravelling before our eyes."

Magna's planned takeover of GM Europe has created a political row in Europe over Germany's role in providing up to £4 billion in bridging loans to Magna.

The EU is planning to probe the deal to ensure that Germany's state aid package has not resulted in unfair practices and given preference to keeping German jobs.