US President Barack Obama has been accused of doing Downing Street’s bidding – after he said the UK would be at “the back of the queue” for American trade deals if it left the EU.
Mr Obama was criticised by pro-Brexit campaigners after he warned of the consequences of the UK leaving the EU.
UKIP’s Nigel Farage said Mr Obama was “talking down Britain”, while Tory Liam Fox said his views were “irrelevant”.
Mr Obama, on a three-day UK visit, will meet Labour leader Jeremy Corbyn later.
His intervention came on his first full day in the UK and comes just weeks ahead of the 23 June in-out referendum.
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Speaking at a joint news conference with Prime Minister David Cameron, Mr Obama said the US “wants Britain’s influence to grow – including within Europe”.
“The UK is at its best when it’s helping to lead a strong European Union. It leverages UK power to be part of the EU.
“I don’t think the EU moderates British influence in the world, it magnifies it.”
However, his intervention in the referendum debate provoked a backlash from Leave campaigners.
Mr Farage accused the US president of doing Mr Cameron’s “bidding” and talking down Britain, adding: “I think that’s shameful.”
Tory former defence secretary Liam Fox said Mr Obama would be leaving the White House in November, and therefore his comments were “largely irrelevant”.
He told BBC’s Newsnight: “We heard ‘you are our best friend, we have a special relationship, and you will get a punishment beating if you leave the EU’.
“This is very much the Downing Street refrain.”
Conservative MP Dominic Raab labelled Mr Obama a “lame-duck American president doing an old British friend a political favour”.
Meanwhile, another prominent Leave campaigner – former cabinet minister Iain Duncan Smith – has used an editorial in the Daily Mail to move the referendum debate on to immigration.
In his editorial, he says that the introduction of a national living wage – a move he supported while in government – will “surely lead to another stampede to our borders”.
He adds: “To make the Living Wage work for British people, we need to be able to control the number of people coming in.”
Dinner at palace
Mr Obama, who is visiting the UK with First Lady Michelle Obama, will spend his second full day of his visit in London on Saturday.
He will meet Labour leader Mr Corbyn and visit London’s Globe Theatre as part of the celebrations marking the 400th anniversary of Shakespeare’s death.
The Obamas were welcomed on Friday evening by the Duke and Duchess of Cambridge and Prince Harry for dinner at Kensington Palace.
Earlier, they had lunch with the Queen and Duke of Edinburgh, and Mr Obama paid tribute to Her Majesty on her 90th birthday, describing her as “truly one of my favourite people”.
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