Westminster's move towards English votes for English laws will make it more difficult to keep the United Kingdom together, according to the former minister who spearheaded the UK Government's opposition to Scottish independence.

Former Scottish Secretary Alistair Carmichael described Thursday's vote to give English MPs a veto over legislation deemed to only affect England as an act of "wanton constitutional vandalism" at the Scottish Liberal Democrat conference in Dunfermline.

Mr Carmichael replaced fellow Lib Dem Michael Moore as Scottish Secretary in the latter stages of the referendum campaign, spearheading the UK Government's successful defence of the UK in Scotland and piloting the first draft of the Scotland Bill at Westminster.

He said English votes for English laws "will foster a sense of grievance in Scotland, Wales and Northern Ireland".

"For those of us who want to see the United Kingdom continue it makes it all the much more difficult," he said.

"It is extremely ironic that in Scotland we have Ruth Davidson telling you that she and she alone can save the union when in London David Cameron, a victim of his own right wing, is systematically undermining it and destroying it.

"The answer is a federal structure for the whole of UK and we are the people that must lead this fight."

Mr Carmichael narrowly defended his Orkney and Shetland seat at the general election in the face of the SNP landslide and collapse of the Lib Dem vote across the UK.

However, he has been called before an election court next month amid accusations that he broke the law when he admitted lying about his role in an SNP smear during the election campaign.

Scottish Lib Dem leader Willie Rennie issued a call to independence supporters to put their constitutional preferences aside and back his party, insisting the SNP government at Holyrood has been found wanting on issues such as health and justice.

Mr Carmichael's speech to conference was immediately preceded by a smattering of applause for Matthew Hall, a new Lib Dem member from Dunfermline and West Fife, when he admitted that he voted Yes in the independence referendum.

"The reason I voted Yes in September wasn't a vote for independence, it was a vote for federalism," he said.

"I don't know when the Liberal Democrats became a unionist party. The Liberal Democrats are a federalist party.

"I was disheartened with the Better Together campaign. We all need to look at what happened to Labour in Scotland to see how badly that can affect a party."

UK Lib Dem leader Tim Farron said Mr Carmichael deserves "a second chance" after his admission that he lied during the general election campaign.

A bid by his lawyers to have the court case against him thrown out failed after the court dismissed a key plank of his defence and called for further evidence on the remaining legal matters.

A four-day Election Court hearing will take place at the Court of Session in Edinburgh from November 9.

In a briefing to journalists at conference, Mr Farron said: "I have no legal training whatsoever so I have no opinion on the legal matter.

"We shouldn't comment, but just that most normal people tend to give people a second chance."

A YouGov poll of over 1,000 people in Scotland earlier this month found over two-thirds (67%) who thought Mr Carmichael should resign as an MP over the matter.

Mr Farron added: "I think it's a reminder, I guess, that we all need to be careful with our language."