Mayor of London Boris Johnson is taking no prisoners in the EU debate, labelling President Barack Obama's plan to tell the British people they should vote to stay in the EU a "piece of outrageous and exorbitant hypocrisy".

Johnson's comments come before Obama plans to land in the UK next month to urge voters to stay in the 28-member bloc, arguing that otherwise it will lose influence and power on the world stage.

"The American view is very clear. Whether in code or en clair, the President will tell us all that UK membership of the EU is right for Britain, right for Europe, and right for America. And why? Because that – or so we will be told – is the only way we can have “influence” in the counsels of the nations," Johnson said.

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He added in his Telegraph column: "It is an important argument, and deserves to be taken seriously. I also think it is wholly fallacious – and coming from Uncle Sam, it is a piece of outrageous and exorbitant hypocrisy."

The mayor claims that the British people will be told to be "good to themselves, to do the right thing", being advised by our most important ally that it is in our interests to stay in the EU, no matter how flawed the UK feels the institution is.

Johnson highlighted the loss of sovereignty as well as the expense, the bureaucracy and the uncontrolled immigration as flawed characteristics of the EU.

The Prime Minister's spokeswomen said: "[The prime minister] said when he was in France at the summit that lots of people are making their views known on this issue, including international leaders, and these are people that wish Britain well and they are worth listening to."

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But the mayor also hit out at the Presidents motivation, arguing the US would never accede to a set of institutions akin to the EU that link Mexico, Canada and the US.

"In urging us to embed ourselves more deeply in the EU’s federalising structures, the Americans are urging us down a course they would never dream of going themselves. That is because they are a nation conceived in liberty. They sometimes seem to forget that we are quite fond of liberty, too," Johnson added.

Meanwhile, chancellor George Osborne yesterday slammed Johnson for suggesting the UK could achieve a Canadian-style free trade deal with the EU. The chancellor said that agreement took seven years to negotiate and some tariffs – notably on cars – still remain in place.