BBC Newsnight presenter Jeremy Paxman has apologised for questioning Liberal Democrat leader Charles Kennedy too closely about his drinking habits.

It follows House of Commons leader Robin Cook's complaint that many MPs were "taken aback and distressed at the degree of personal questioning" during Paxman's Newsnight programme that was broadcast on Wednesday evening.

Maybe there was one question too many on drink

Jeremy Paxman

During the interview, Mr Paxman told Mr Kennedy that every politician his programme had spoken to in preparing for the meeting had said: "You're interviewing Charles Kennedy - I hope he's sober."

The Lib Dem leader dismissed the comments as the "kind of thing that goes around the hothouse of Westminster".

"It matters if people allow that kind of rumour or allegation or slur to achieve a level of prominence that it doesn't otherwise require," he said.

'Moderate drinker'

Told that MPs from his own party were among those contacted by Newsnight, Mr Kennedy pointed out that he had just been re-elected unanimously as leader by Lib Dem members.

He said he drank "moderately and socially".

Mr Paxman also asked if he drank privately "by yourself, a bottle of whisky late at night"?

"No I do not," Mr Kennedy replied.

Mr Kennedy is shortly to wed

On Thursday, the BBC defended Mr Paxman's line of questioning, while the presenter said he was sorry for any offence caused.

"The questions put to Charles Kennedy about his personal life made up a short section at the end of an interview which largely comprised tough questions about policy and the Liberal Democrats' political philosophy," said a BBC spokesman.

"Mr Kennedy has answered questions about social drinking on several occasions in the past from print and broadcast journalists.

"It was not unfair for Jeremy Paxman to touch on the matter."

'One too many'

Mr Paxman added: "I have always found Charles Kennedy an affable chap.

"I am sorry if any offence has been caused. Maybe there was one question too many on drink."

When the mud is thrown, there is a tendency for the mud to stick and difficult to dispose of

Robin Cook

Mr Paxman spoke out after Labour MP Jonathan Shaw said questions in the Newsnight interview were "highly personal and irrelevant to political debate", which did nothing to enhance parliament or the BBC.

Mr Cook agreed, stressing that "when the mud is thrown, there is a tendency for the mud to stick and difficult to dispose of".

He said the BBC needed to reflect that it was a public service broadcaster, and it "should not seek to dumb down and compete with the bottom end of the market".

Wedding bells

During the wide-ranging interview the Lib Dem leader was also quizzed on his forthcoming marriage to Sarah Gurling.

Mr Paxman asked him: "Many people in this day and age decide not to do that but you are making a very public statement in deciding to get married?"

Mr Kennedy said: "Yes and so is Sarah making a very public statement, which in a way rather comes back to your last rather more personal set of questions.

"Anybody who knows Sarah Gurling knows that she's also an extremely serious-minded, career orientated person in her own right.

"She would not enter into something like this unless there was a fundament of seriousness about us and about our relationship."

Asked whether Ms Gurling kept him on the straight and narrow he said: "I suspect you should answer that rather than me. I suspect she rather does."