Engine maker Rolls-Royce could build an aircraft testing plant abroad instead of at its British factory.

The decision to consider moving to Germany or the U.S. could see thousands of vacancies created -- at a time when jobs for British workers remain a priority.

The company told staff it is looking at the feasibility of constructing an aircraft engine testing plant abroad instead of at its UK base in Derby.

The move is another blow for the manufacturing industry just weeks after 1,400 workers lost their jobs at train maker Bombardier, also in Derby, after the Government said a 1.4 billion pounds contract would go to Siemens in Germany.

Rolls-Royce workers were told the news last week, which created an air of uncertainty.

The Derby plant, which has 10,000 staff and is one of the biggest manufacturing employers in the country, is not under threat. But unions were concerned about the long-term impact of the move.

Adrian Axtell, Unite regional secretary for the East Midlands, said: A significant number of jobs in Derby are linked to development projects.

Rolls-Royce, with the support of the Government, needs to do everything possible to maintain its development projects in Derby in the long term.

It is not the first time the company has been criticised for creating jobs overseas instead of in Britain. Last year it opened a testing centre on the outskirts of Berlin, employing 70 skilled workers.

Rolls-Royce -- not to be confused with its carmaker namesake after the two split in 1973 -- claimed the testing facility would mean it can produce its engines at the rate its customers are demanding.

A spokesman said: Rolls-Royce is investing billions of pounds in the UK and around the world. The company needs to double the number of Trent engines it produces to power the next generation of wide-body planes.

We have confirmed we will assemble and test Trent XWB engines... in Derby. This will sustain jobs at Rolls-Royce as well as in the hundreds of British companies in our supply chain.