A controversial interview in which Charles Kennedy was quizzed by the BBC's Jeremy Paxman over his drinking habits was "overly intrusive", the Broadcasting Standards Commission (BSC) has said.
Mr Kennedy was just about to get married
The Newsnight presenter apologised at the time for going too far when he asked the Liberal Democrat leader about whether he drank alone at night.
Mr Paxman conceded that he had asked "one question too many".
The BSC said: "The presenter's prolonged questioning of Mr Kennedy in
relation to personal matters had been overly intrusive in nature and tone and
had exceeded acceptable boundaries for broadcast."
A spokesman for the Lib Dem leader told BBC News Online: "Jeremy Paxman accepted after the interview that he was wrong and publicly apologised.
"Charles Kennedy considers the matter closed."
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.
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 Paxman said after the interview was raised in the House of Commons: "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."
During the wide-ranging interview the Lib Dem leader was also asked about his marriage to Sarah Gurling - which took place just days later.
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.
Mr Paxman later apologised
"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."