The row over the "resignation" of Martin Sixsmith has rebounded on Robin Cook, who has apologised for misleading MPs.

In business questions in the Commons on Thursday, Cook made a personal statement regretting his claim that there was "no email" sent from Sixsmith to Stephen Byers' special adviser Jo Moore.

"At the time [of the last business questions] I said there was no disagreement between Mr Sixsmith and Jo Moore, which I accept is difficult to reconcile with all we have since learned," Cook said.

"More seriously, I said there was no such email. The Mirror has since recorded that it was misled as to the contents of the email and that it was not addressed to Jo Moore, but there was an email. I would not have used those words had I been aware of that at the time.

"I enjoy our Thursday exchanges. I always seek to be accurate, if combative, in my reply. I regret that on the last occasion I was not in possession of accurate information. I apologise to the House for in all good faith having misled it, and to the Mirror for having done it an injustice," said Cook.

The shadow leader of the Commons, Eric Forth, thanked Cook for "what he has just said so graciously".

"Just to round off that little matter, the leader may want to come to the House on another occasion following the inquiries that I have no doubt he is continuing to make as to the source of the misinformation he was so regrettably given, and the actions he and the cabinet propose to take to ensure such matters don't happen again," Forth suggested.

Paul Tyler of the Liberal Democrats added: "I do hope that other members of the cabinet will follow his example in future."