Honda may be planning to sideline its car manufacturing plant in Swindon because Britain under Gordon Brown “shows no sign of joining the euro”.

The comments yesterday by Takeo Fukui, the president of the Japanese car giant, are the strongest danger signal ever raised over the future of Honda’s plant in Swindon.

Mr Fukui acknowledged in May that the facility in Wiltshire had been “something of a mistake”.

Mr Fukui has already said that he has no plans to expand Honda’s operations in the UK.

He strongly hinted yesterday that Swindon would eventually be reduced to building cars only for the British market, rather than becoming the European manufacturing hub that it was originally intended to be.

“When we built our factory in Swindon,” he said, “we did so because the UK suggested it would join the eurozone.

"On closer inspection, it now seems definite that Britain will not join the euro, so we may need to come up with other options to supply cars to Europe.”

Mr Fukui added that 15 years since being built, only half of the Swindon plant’s present output is sold into the British market, raising concerns that as the factory is reduced to supply only UK customers, its overall capacity will be cut back.

In 2003 Mr Fukui was among a small group of Japanese carmakers who hosted Tony Blair at a meeting near Mount Fuji, where they pressed the former prime minister on his intentions over the euro.

Asked whether he was likely to lobby Gordon Brown in a similar way, Mr Fukui said: “We don’t expect Britain to join just because we ask — all we can do is state our position.”

Honda’s investment plans in Europe are likely to focus on eurozone countries and Turkey, where it already has a factory.

In a recent interview with The Times, Carlos Ghosn, the Nissan chief executive, said that he did not regard Britain’s failure to join the euro as a reason to pull back from investment in the UK.

He said that he would “fight hard” to maintain the competitiveness of the company’s plant in Sunderland.

Yesterday Honda announced big expansion plans for East Asia. The company said that it would become the world's first foreign carmaker to develop and market cars under an original brand in China.

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