The UK Government has been warned against "imposing a fatwa" and blocking a second independence referendum, "however unwelcome" such a vote may be.

Former deputy prime minister Nick Clegg said Theresa May's government should not obstruct another ballot on independence if this was "being pushed" by the SNP.

He also argued the Prime Minister may not be the best person to lead a campaign to keep the United Kingdom together, saying she may not be politically agile enough to deal with a fast-moving referendum campaign.

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The former Liberal Democrat leader spoke out on the prospect of a second vote on independence ahead of a speech at his party's Scottish conference in Perth.

Asked whether Westminster should refuse to grant Holyrood the power to hold a legally-binding vote, Mr Clegg told journalists: "I think it would be very difficult for any government of any composition in London to try and impose a fatwa on any move towards a referendum if that was something that was being pushed - however unwelcome it is, and indeed it is unwelcome to the Liberal Democrats.

"Do we think a solution to a country careering towards hard Brexit is to have another divisive and all-absorbing referendum about whether the United Kingdom survives or not? No, we don't."

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Mr Clegg refused to offer any "guesswork" about what would happen if Scots were given another chance to vote on independence

"I would have thought all sides would want to have a good look at how campaigns were fought in the past and what can be improved and changed from those previous experiences, but that's stating the bleeding obvious," he said

"No contest is going to be a carbon copy of a previous one, it will be very much shaped by the stories, the personalities, the issues that pop up."

Mr Clegg, who worked with Mrs May while in coalition government with the Conservatives, described her as a "thorough" and "methodical politician".

He added: "There's a certain rigidity, I don't think she'd ever call herself a particularly agile, innovative politician.

"Her strengths are when she is in control of all the facts and can methodically go through them. She's not a politician who I sense is very comfortable when she has to react to events.

"It has strengths and weaknesses, it has strengths because it is a very deliberate, methodical way of working, but the weakness which may well manifest itself in both election campaigns and referenda campaigns is these are very fast-moving events in which you don't control all the factors."

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He later told the conference there was an "almost umbilical link" between the English nationalism of a hard Brexit Conservative Party and the "absolute fixation that the SNP have to push yet another referendum on independence here in Scotland".

Mr Clegg said: "They are almost like political cousins, they rely on each other, they are the perfect foils for each other.

"They loathe each other but need each other. They are both political cousins and terrible twins. They are the ying and yang of British politics.

"If they are allowed to trap the rest of us into this dismal tailspin where the choices before us are one for disaggregation and pulling the United Kingdom out of the European Union, matched only by a rival form of disaggregation, a nationalism pulling Scotland out of the successful family of nations of the United Kingdom, then all of us will suffer."

The former Liberal Democrat leader said there was "clearly a strong and increasing desire on the part of the SNP to have another tilt" at an independence referendum.

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He said the nationalists were "invoking the rigid drive towards a hard Brexit by the Conservatives as their most proximate alibi for doing so".

He added: "At the moment we're in this kind of tailspin where the Conservative Party's hellbent determination on a hard Brexit is being supplemented and accompanied by the SNP's hellbent determination to deliver another referendum. They sort of feed off each other.

"The key challenge in British politics, from my point of view, is the need to stop that tailspin before things get seriously out of hand and we see not only immense damage to the United Kingdom as a whole by a badly administered Brexit, but that we also end up in the process losing the family of nations in the United Kingdom to boot. That's something we want to fight on all fronts."