Nissan has joined a chorus of criticism from the world's leading carmakers about the strength of sterling, shaking Britain's reputation as the location of choice in Europe.

Echoing complaints from Ford, General Motors, Honda, Toyota and BMW of Germany, Mr Carlos Ghosn, Nissan's president, said the strong pound was forcing the company to consider shifting new investment to the euro zone.

His comments put a cloud over the future of Nissan's plant in Sunderland, the most productive car plant in Europe.

It also adds to the pressure on British Prime Minister, Mr Tony Blair, to make a firmer commitment to joining the euro.

Separately yesterday in Germany, where he was meeting the German Chancellor Mr Gerhard Schroder, Mr Blair said Britain wanted to join Europe's single currency, but would do so only if its economic tests for euro entry were satisfied.

"Being part of the European Union is good for Britain, it is good for British jobs, it is good for British people," Mr Blair said. "We should be full players in Europe."

Carmakers in Britain have blamed the euro's persistent weakness against sterling for undermining their profitability in Europe. Nissan lost 38.1 billion yen (€3.83 billion) in the region last year.

Mr Ghosn said Nissan had no intention of closing the Sunderland plant, but said currency issues could jeopardise a potential £150 million expansion there. He is leading a 1,000 billion yen worldwide restructuring of Nissan.

He said the Sunderland plant, which employs 5,000 people, faced its biggest threat since opening in 1986.

Mr Ghosn said Nissan would decide by the year end whether to build its next generation Micra small car at Sunderland.