Brexit would leave UK at back of the queue on trade: Obama

Outcome of June 23 referendum is a matter of "deep interest" to the US, because it "affects our prosperity as well", Obama says

US President Barack Obama has said Britain would go to the "back of the queue" for trade deals with America if it evotes to leave the European Union in the June 23 referendum.

The outcome of the decision is a matter of "deep interest" to the US, because it "affects our prosperity as well", he said here.

"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," he said.

"America wants Britain's influence to grow, including within Europe," added Obama, standing alongside Prime Minister David Cameron at a press conference at the Foreign Office yesterday.

When asked what would happen if Britain voted to quit, Obama said that while "maybe at some point" it could seal a trade deal with the US, "it's not going to happen any time soon".

"The UK's going to be at the back of the queue," he said at the start of a three-day visit to the UK that has been dominated by his strong intervention in favour of Britain voting to stay within the 28-country bloc in the June 23 referendum.

Cameron said being a member of the EU strengthened Britain's "special relationship".

On the UK's upcoming referendum on its EU membership, he said: "This is our choice - nobody else's - the sovereign choice of the British people. But as we make that choice, it surely makes sense to listen to what our friends think."

On whether he should be intervening on the UK's referendum, Obama said: "Let me be clear: ultimately this is something the British voters have to decide for themselves.

"As part of our special relationship, part of being friends is to be honest and to let you know what I think, and speaking honestly, the outcome of that decision is a matter of deep interest to the US, because it affects our prosperity as well."

His remarks drew a furious reaction from those in favour of a Brexit, with London mayor Boris Johnson even alluding to his anti-colonial sentiments and "part-Kenyan" ancestry.

"I love Winston Churchill, love the guy," he told reporters in reference to Johnson's claims that he had moved Britain's war-time Prime Minister's bust out of the Oval Office in the White House.

"There's only so many tables where you can put busts, otherwise it starts looking a little cluttered," he explained.

Obama will be heading to Germany at the end of his three-nation tour which also included Saudi Arabia.