Boris Johnson has accused President Obama of trying to bully British people into voting to remain a member of the European Union.
The London mayor has been heavily criticised and accused of racism for suggesting Obama has an "ancestral dislike” of the United Kingdom because he is "part-Kenyan".
Speaking outside his London home this morning, Johnson dodged direct questions about wether his comment was "dog-whistle racism" - instead dismissing the claim the UK would suffer outside the EU.
"I think it is absolutely ridiculous that the United Kingdom is now being told it has to go to the back of the queue for any free trade deal," he said.
"The reason we haven’t had a free trade deal in the last 43 years is that we are part of the EU. If we get out, we will have a huge opportunity to intensify our trade, not just with Europe but with the rest of the world."
He added of the president's intervention: "So, for us to be bullied in this way, I don’t want to exaggerate, for people to say that we are going to be unable to cope on our own is absolutely wrong."
Obama had said the UK would be at the "back of the queue" for any trade deal with the US in the event of Brexit.
Iain Duncan Smith, the former work and pensions secretary and leading Brexit campaigner, today defended Johnson.
He said the London mayor "simply referred to some of the reasons why he [Obama] may have a particular lack of regard for the UK".
“I know Boris very well in no way can you describe him as that. He has fought against that time and time again as I have, any kind of racism,” he told BBC Radio 4’s Today programme.
Asked whether it was possible to see a “racist dog-whistle” in Boris’ comment, the former work and pensions secretary said "no, you can’t"