Councillor George Leslie has stepped down as chairman of the housing and communities committee without chairing a single meeting, and will now continue as an independent for his Kirkcaldy East ward.
Cllr Leslie said he had been forced to resign following a witch-hunt by other party members, who he claimed had behaved "abysmally" towards him after he nominated independent councillor Andrew Rodger as licensing board chairman against the wishes of certain SNP councillors.
He said: "It saddens me to have to make this decision. I want to make it crystal clear that I fully embrace the SNP government nationally and have given my full support to the coalition within Fife Council.
"What has lead to my resignation is that I took a decision based on the criteria set before me regarding the election of Convener of the Licensing Board. This did not meet with certain members of my party at Fife House.
"The actions I took on the Convener's position were honourable - the board is non-political, no discussions are allowed in private regarding nominations. This is what I adhered to what has brought about my removal from office."
Cllr Leslie - an SNP member for 45 years, and councillor for 30 - also rubbished suggestions that consideration for his health had led colleagues to call into question his abilities.
His position as chairman was due to be considered at a full council meeting next month, where the option to remove him from the post would have been put to a vote.
"If I had been given the chance to prove my capabilities and thought the job was affecting my health I would have stood down of my own accord," he added.
Operating as an independent nationalist, Cllr Leslie has vowed to continue to serve out his four year term.
"My motto has always been to put my constituents first and put their views across as well as my own to make sure the public of Kirkcaldy know that I am on their side."
SNP leader Peter Grant denied the vote had anything to do with Cllr Leslie's nomination at the licensing board, explaining his role as chairman had been reviewed after party members had raised concerns over whether he would be able to cope with such a demanding job.
Cllr Grant, who is also leader of the administration, said: "I am disappointed with what George has done and concerned that he doesn't seem to be able to accept the reasons.
"This was not because of what happened at the licensing board, however, that was just one example which caused members to question his ability to do the job.
"We made a mistake when we put him forward as chairman and I hold my hands up to that. I realise this would have been hurtful to him but we just didn't feel George was capable of doing the job for four years.
"I'm bitterly disappointed that he has now excluded himself from the party, especially after he gave assurances that he wouldn't."