A former SNP councillor has written an open letter to Jim Sillars calling on him to quit the party.

Edinburgh councillor Jim Orr said he felt compelled to write the letter after Mr Sillars 'appeared to taunt the SNP' by saying he 'couldn't care less' if the party expelled him for campaigning in support of Rise.

The councillor, who quit the SNP over in 2014 over 'internal spats', said that he had lost faith in Mr Sillars and told him to 'do the decent thing and resign'.

In the letter, published in the Scotsman, Mr Orr wrote: "I have a lot of admiration for you Jim but I've lost faith in you. If you believe in Rise, then go and join them and put your heart and soul into helping them.

"If you're an honourable man you will do the decent thing and resign from the SNP rather than have the last years of your often distinguished career become synonymous with goading the SNP to dare to expel you."

Mr Orr also claimed that Mr Sillars' 'day of reckoning' comment had undermined the credibility of the Yes campaign during the independence referendum.

He said: "To your credit, you campaigned hard and well for independence up to the September 2014 referendum. But then you did more to undermine the credibility and positive ethos of the Yes campaign than anyone else on our side when you issued your “Day of Reckoning” threat to No supporters.

"This was a hammer blow. Tens of thousands of No voters saw a bitter and twisted side of the Yes campaign that actually barely exists outside of groups like the so-called Scottish Resistance."

Mr Sillars said that he did not fear being expelled by the SNP as he launched Rise's Glasgow campaign with Cat Boyd and two other candidates in Govan last week.

His speech threw down the gauntlet to SNP HQ, where officials have already discussed his backing of RISE on the list vote, in defiance of the party’s ‘Both Votes SNP’ message.

It is against SNP rules to campaign for a rival party in an election.

Speaking at the Glasgow launch, Mr Sillars said: “I don’t think I’m actually in any danger of being expelled and therefore joining the pantheon of Alex Salmond, Margo MacDonald, Kenny MacAskill. They’ve all been expelled but I never have been.”