Mayor of London ... Boris Johnson has accused US President Barack Obama of “hypocrisy” over his support for the UK remaining in the EU. Picture: Getty.

The London mayor, who backs EU exit, told the BBC the Americans “wouldn’t dream of sharing [their] sovereignty” as the UK had done.

The US president is expected to repeat his support for Britain’s EU membership when he visits the UK next week.

The White House has indicated Mr Obama is ready to offer his view but will stress the decision is for UK voters.

Speaking in Washington, Chancellor George Osborne said it was the “overwhelming view” of foreign governments and international institutions such as the IMF and NATO that the UK should remain.

Backing from Mr Obama could boost Prime Minister David Cameron’s efforts to persuade the country to vote to remain in the EU in the 23 June referendum.