Boris Johnson grilled today over his personal integrity.

London Mayor Boris Johnson faced a series of questions about his personal integrity in an awkward TV interview, which culminated with him being accused of being "a nasty piece of work".

A visibly uncomfortable Johnson struggled when confronted with accusations that are due to be aired in a documentary by filmmaker Michael Cockerell on Monday 25 March.

Appearing on the BBC's Andrew Marr Show on Sunday 24 March, stand-in presenter Eddie Mair quizzed Johnson about fabricating a quote when working as a journalist at the Times over a decade ago, which led to him being sacked.

Johnson said: "I mildly sandpapered something someone had said. It is very embarrassing, and I am very sorry about it."

He was then grilled about allegations he lied to then Tory leader Michael Howard over an extra-marital affair when serving as shadow arts minister.

"I never had any conversation with Michael Howard about that matter," the mayor replied. "I do not propose to go into all that again. Why should I? I've been through it a lot. Why don't we talk about something else?"

Mair then confronted Johnson over a recording in which a fellow old Etonian friend requests the address of a journalist so he could have him beaten up, and Johnson seems to agree.

"I think if any of us had our phone conversations bugged people say all sorts of fantastical things whilst talking to their friends."

"You are a nasty piece of work, aren't you?" Mair said, prompting Johnson to say the interpretation being given to the incidents was "not wholly fair".

He was then asked whether he had ambitions to be prime minister, to which he responded, "What I want is for David Cameron to win this election, which he deserves to do."

"In these circumstances it is completely nonsensical for me to indulge this increasingly hysterical conversation."