Former Scottish secretary Alistair Carmichael has admitted he was the one who leaked a memo which claimed SNP leader Nicola Sturgeon would prefer the Conservatives to win the general election.
Carmichael, a Liberal Democrat, admitted it was a "error of judgement" to leak a document which said Sturgeon would rather back David Cameron over Ed Miliband during a conversation with the Sylvie Bermann, the French ambassador in February.
A Whitehall inquiry was launched to determine who leaked the document which risked having huge implications in the result of the election.
Carmichael previously denied suggestions he could be responsible for the leak, however, following the release of the report, Carmichael now accepts "full responsibility" and has said he will not be accepting his ministerial severance pay as a result.
The report states Carmichael had given permission to his then special adviser Euan Roddin to release the memo.
It adds: "He [Roddin] told the investigation team that he acted in what he saw as the public interest and that in his view the public needed to be aware of the position attributed to the first minister.
"Carmichael confirmed that he had been asked by Mr Roddin for his view of the possibility of sharing the memo with the press. Mr Carmichael agreed that this should occur. He recognises that, as a secretary of state, he was responsible for his own conduct and that of his special adviser.
"He could and should have stopped the sharing of the memo and accordingly accepts responsibility for what occurred."
Carmichael said: "I had not seen the document before it was published in the Daily Telegraph, however I was aware of its content and agreed that my special adviser should make it public.
"I should not have agreed this. It was an error of judgement which I regret. I accept full responsibility for the publication of the document.
"I have written today to the first minister and to the French ambassador to apologise to them both.
"Had I still been a government minister I would have considered this to be a matter that required my resignation. I have therefore informed the cabinet secretary that I will decline my ministerial severance payment."
The leaked memo read: "Just had a telephone conversation with Pierre-Alain Coffinier (PAC), the French CG [consul-general]. He was keen to fill me in on some of the conversations his ambassador had during her visit to Scotland last week. All of this was given on a confidential basis.
"The ambassador....had a truncated meeting with the FM [Nicola Sturgeon, the first minister] (FM running late after a busy Thursday...). Discussion appears to have focused mainly on the political situation, with the FM stating that she wouldn't want a formal coalition with Labour; that the SNP would almost certainly have a large number of seats... that she'd rather see David Cameron remain as PM (and didn't see Ed Miliband as PM material)."