Veteran journalist Jeremy Paxman was forced to apologise after using a swear word during Newsnight.
The broadcaster read a direct quote from Andrew Rawnsley's book on the inner workings of New Labour which said: "(Gordon) Brown went berserk with Bob Shrum. 'How could you do this to me, Bob?' Brown screamed at a shaking Shrum. 'How could you f**king do this to me?"'
A few minutes later Paxman apologised to viewers for his colourful language.
He said: "Apparently I'm told by our editor I have to apologise for quoting what you said the Prime Minister said and using the f word there. So honour satisfied now."
Rawnsley's book caused political shockwaves with allegations of bullying behaviour by the Prime Minister.
A BBC spokesman said: "During a post watershed interview with Andrew Rawnsley Jeremy read a direct quote from his book which contained an expletive. He apologised immediately to anyone that may have found it offensive."