The Mayor of London has called Barack Obama's intervention in the EU referendum debate a "piece of outrageous and exorbitant hypocrisy".
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 Boris Johnson.
Mr Johnson - who was born in New York - 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: