Image caption Willie Rennie said the recent events were an "aberration"

Willie Rennie has offered his backing to former Scottish Secretary Alistair Carmichael, who is facing calls to resign over a leaked memo.

The document, released before the general election, had suggested that Nicola Sturgeon wanted David Cameron to remain as prime minister.

Scottish Lib Dem leader Mr Rennie said Mr Carmichael, the Orkney and Shetland MP, deserved a "second chance".

The SNP said Mr Carmichael faced a "credibility crisis".

The party has highlighted previous comments made by Mr Carmichael which it said was in breach of his own code.

'An aberration'

Mr Rennie said: "He deeply regrets his actions, has accepted responsibility for his error of judgement, apologised to Nicola Sturgeon and the French ambassador and declined his ministerial severance payment.

"I have known Alistair for almost thirty years and have worked closely with him in parliament for almost a decade. I have always been impressed by his energy, dedication and professionalism.

"It is clear to me that recent events are an aberration.

Image copyright PA Image caption Alistair Carmichael's former special adviser Euan Roddin leaked the memo with his permission

"As a liberal I believe that people deserve a second chance. I hope fair-minded people would agree that Alistair Carmichael should be given that second chance."

On Saturday the Scottish Liberal Democrat Party executive agreed Mr Carmichael would not face any disciplinary action.

The leaked memo was a third-hand account of a conversation between Nicola Sturgeon and the French ambassador, in which Ms Sturgeon was reported to have said she wanted David Cameron to remain as prime minister. Both the first minister and the ambassador insisted this was not said.

SNP leader Ms Sturgeon previously called for Mr Carmichael to consider his position as an MP and described the leak of the confidential memo as a "blatant election dirty trick".

The Nationalists have highlighted Mr Carmichael's response to Labour MP Phil Woolas' dishonest campaign in the 2010 general election, for which an election court found Mr Woolas guilty of illegal practice under the Representation of The People Act 1983.

Code breach

In a Shetland Times feature from November 2010, Mr Carmichael wrote: "The right to freedom of speech is a fundamental one but it does bring a responsibility with it to tell the truth. The right to smear an opponent is not one we should be defending."

The SNP also pointed out that Mr Carmichael supported the 2009 Early Day Motion for parliamentary elections (recall and primaries) bill on the right of voters to recall their MP in certain specified circumstances.

Mike McKenzie, SNP MSP for the Highlands and Islands, said: "Just when Mr Carmichael thought things couldn't get any worse he has been caught in breach of his own code - and this further deepens the credibility crisis he now finds himself in.

"Mr Carmichael misled his constituents during an election, and the only way that he can relieve the pressure he is under is to stand down."

He added: "Mr Carmichael's majority plummeted from nearly 10,000 to just over 800, and there appears to be a very strong reaction in Orkney and Shetland against him this weekend. The people in his constituency deserve to know the whole truth, and in my view would be best served by Mr Carmichael standing down."

Protests have been held in Kirkwall, Orkney, and Lerwick, Shetland, calling for Mr Carmichael to resign.

The confidential memo was published by the Daily Telegraph on 3 April as the general election campaign got under way.

It was written by a civil servant in the Scotland Office and claimed Ms Sturgeon told the French Ambassador to the UK, Sylvie Bermann, that she would prefer Mr Cameron, the leader of the Conservatives, to remain as prime minister.

The memo also claimed Ms Sturgeon said that Ed Miliband, who was then Labour's leader, was not prime minister material.

Ms Sturgeon and the ambassador both said it was incorrect.

The official cabinet office inquiry into the leaking of the memo said Mr Carmichael's former special adviser Euan Roddin gave the details to the Daily Telegraph - but he had Mr Carmichael's permission to do so.

Mr Carmichael said, while he had not seen the document before it was published by the newspaper, he was "aware of its content and agreed that my special adviser should make it public".