Three Plaid Cymru Councillors in Cardiff have announced that they are resigning from the party.
Cllr Keith Parry, the Plaid group leader on Cardiff council, and Cllrs Lisa Ford and Andrea Gibson said they would now sit as an independent group.
They said their decision to leave was motivated by the treatment of former Plaid Cymru AM, Neil McEvoy, who had been expelled from the party.
They said that they have kept quiet “in the interests of unity” but could not continue to do so.
“After coming within 1,000 votes of defeating the current First Minister in Cardiff West, after the hard work of so many fantastic members, our AM, Neil McEvoy, was expelled from the party,” they said in a statement.
“His application was then rigged to prevent his re-entry to Plaid.
“And during our historic win in the Ely by-election, the current Chair and Chief Executive went out of their way to prevent our victory. We managed to win by defying their orders.
“The final straw was the South Wales Central regional representative announcing at Plaid conference that he would support any candidate that had not been nominated by Cardiff West.”
Cllrs Keith Parry and Lisa Ford represent Fairwater alongside Neil McEvoy, while Cllr Andrea Gibson represents Ely.
A Plaid Cymru spokesperson said: “We thank the councillors for their contribution and wish them well for the future.”
The three councillors added that new leader Adam Price had been unwilling to intervene in any way to try to achieve a way forward.
“It is regrettable that ongoing personal vendettas now seem the most important thing for the Plaid Cymru leadership,” they said. “Members are encouraged to make complaints against other members and a toxic atmosphere within the party has been allowed to take hold.
“It is our belief that many at the top of Plaid Cymru have become far too close to Labour and are more interested in cosying up to them than beating them. As elected Councillors who have all beaten Labour, we find this unforgivable.
“We will now continue to represent our communities to the best of our ability, without the stifling hand of the Plaid Cymru leadership.”