Barack Obama's intervention in the EU referendum debate is a "piece of outrageous and exorbitant hypocrisy", Boris Johnson has claimed.
The US president's warnings that Britain will lose influence on the world stage if it quits the 28-member bloc are also "wholly fallacious", according to the London Mayor.
New York-born Mr Johnson attacked the US for interfering in the debate, when it defends its own sovereignty with "hysterical vigilance".
Downing Street has refused to comment on reports that the US president, who has previously made it clear that America wants its closest ally to remain part of the EU, is heading to the UK next month to make the case to voters.
In his regular Daily Telegraph column, Mr Johnson wrote: "Sometime in the next couple of months we are told that president Obama himself is going to arrive in this country, like some deus ex machina, to pronounce on the matter.
"Air Force One will touch down; a lectern with the presidential seal will be erected. The British people will be told to be good to themselves, to do the right thing. We will be informed by our most important ally that it is in our interests to stay in the EU, no matter how flawed we may feel that organisation to be.
"Never mind the loss of sovereignty; never mind the expense and the bureaucracy and the uncontrolled immigration. 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 councils of the nations. 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.
"There is no country in the world that defends its own sovereignty with such hysterical vigilance as the United States of America. This is a nation born from its glorious refusal to accept overseas control."
Mr Johnson, meanwhile, has come in for criticism from George Osborne for suggesting Britain could achieve a Canadian-style trade deal. The Chancellor insisted the agreement took seven years to negotiate and tariffs on exports remain in place for cars and beef.
"I hear people saying 'I want Britain to be like Switzerland, I want Britain to be like Norway, I want Britain to be like Canada'. You know what? I want Britain to be like Great Britain'," Mr Osborne told BBC One's Andrew Marr Show.
Mr Osborne also appeared to take a more personal swipe at the mayor, who came in for criticism over his performance during a recent appearance on the programme.
"If people want a politician who is just going to sit here and blather away and not actually do anything, then get someone else," he said.