LONDON (Reuters) - Japanese Prime Minister Shinzo Abe cautioned Britain on Thursday that a vote to leave the European Union in June’s referendum on membership would make Britain less attractive for Japanese investors.

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His intervention comes less than two weeks since U.S. President Barack Obama bluntly warned Britain that it would be “in the back of the queue” for a trade deal with the United States if it dropped out of the EU.

“Japan very clearly would prefer Britain to remain within the EU,” Abe told reporters during a visit to London. “Many Japanese companies set up their operations in the UK precisely because the UK is a gateway to the EU.”

He added: “A vote to leave would make the UK less attractive as a destination for Japanese investment.”

Speaking through a translator at a news conference with Prime Minister David Cameron, Abe said about 1,000 Japanese companies operate in the UK employing 140,000 people.

But supporters of a British exit from the 28-nation bloc poured cold water on Abe’s comments saying Japanese companies such as Toyota, Nissan and Hitachi were committed to investing in the United Kingdom regardless of the outcome.

“Japan wouldn’t accept the huge loss of control Britain has suffered because of our EU membership, so much of the public will be sceptical of the Japanese prime minister’s ‘do as I say, not as we do attitude,’” said Matthew Elliott, Chief Executive of the Vote Leave campaign.

Cameron said Britain benefited more from Japanese investment than from any other country apart from the United States. He said Japan had investments worth a total of 38 billion pounds in Britain.

“Japanese firms see Britain as the gateway to Europe,” said Cameron, who called the referendum and is leading the campaign to keep Britain in the club it joined in 1973.

A British exit would unleash volatility in foreign currency, stock and bond markets, undermine post-World War Two European efforts toward integration and raise questions about the 21st Century fate of Britain’s $2.9 trillion economy.

“Britain’s friends around the world, including Japan, will be watching your decision on June 23 with very close attention,” Abe said.

Abe is the latest world leader to lend support to Cameron’s call for Britons to vote to stay in the EU.

Last October, Chinese President Xi Jinping said he wanted to see a united European Union and that he hoped Britain would play a leading role in deepening China-EU ties.