British Foreign Secretary Boris Johnson has been forced to defend himself over previous comments he made about Barack Obama and Hillary Clinton.

It happened during a sometimes awkward press conference in London with US Secretary of State John Kerry.

Mr Johnson was challenged by American journalists about "outright lies" he had told and articles he had written about the current US president and his potential successor.

The MP tried to make light of the questions, saying there was a "rich thesaurus" of comments he had made in his journalistic career.

He also joked that it would take "too long" to apologise for all the things he had written which had been "misconstrued".

Mr Johnson was asked by one reporter about his reference to Mr Obama's "part-Kenyan" ancestry during the EU referendum campaign.

He was also reminded he had compared presumptive Democratic nominee Hillary Clinton to a "sadistic nurse in a mental hospital" or Lady Macbeth.

'A rich thesaurus of things'

Mr Johnson replied: "I'm afraid there is such a rich thesaurus now of things that I have said that have been...somehow misconstrued that it would really take me too long to engage in a full global itinerary of apology."

"Most people who read these things in their proper context can see exactly what was intended and indeed I find that virtually everybody I have met so far in this job understands that very well."

Mr Kerry was challenged over Mr Obama's suggestion that the UK would be at the "back of the queue" for a trade deal following Brexit because Washington would rather negotiate with a larger bloc.

He answered: "Yes, it is a fact president Obama and I both said we thought we would be better off with a continuation of UK's membership within the EU, and that's a well-known fact."

"But that's not the way the people of this country voted. We respect democracy, all of us."

Asked for his views on his new counterpart, Mr Kerry said he had been told by Washington's ambassador to the EU, who went to Oxford with him, he was "very smart and capable man".

Mr Johnson joked: "I can live with that", to which Mr Kerry replied: "It's called diplomacy, Boris."

Earlier Mr Kerry had talks with British Prime Minister Theresa May.

They got off to a bumpy start when he banged his head on the door to Number 10 Downing Street.