SNP councillors voted down an attempt to reverse controversial cuts to paid trade union convener posts amid a fiery meeting on Monday.

Labour members and Community Party councillor Jim Bollan forced the meeting over the reduction of the posts from 3.4 to two.

The SNP has repeatedly cited the public consultation earlier this year as backing their £50,000 cut. But union officials have hit back fiercely and claimed the move at March’s budget meeting was a prelude to cutting staff.

Several councillors, on both sides, noted their union membership while a large and loud crowd of union members cheered or heckled from the public benches after moving their protest indoors.

Speaking before the meeting, union leaders said they hoped the paid convener cuts would be reversed and cited wide member and public support.

Councillor David McBride, who raised the motion prompting the unusual 9am council meeting in Clydebank, criticised the West Dunbartonshire SNP for attacking trade unions even while their national leader, First Minister Nicola Sturgeon has backed them.

Cllr McBride said: “The SNP have behaved in a despicable fashion. For this one time only, I support Nicola.”

Council leader Jonathan McColl said Labour were trying to prevent management having individual meetings with staff and that everything called for in the Labour motion was already being done.

He said: “This meeting is an absolute waste of time because we are already doing what the motion asks.”We hope the use of facility time increases. We provide over and above what it says in the agreement – we provide for facilities for five conveners, not three.”

Cllr McColl also condemned “misleading information from senior trade union reps” being put out and insisted, “we are not amending the local agreement in any way”.

Cllr Bollan said the SNP had torn up the facility time agreement with the unions and as a result, staff had ended their partnership agreement with the council, risking employee relations and services to the public.

He said: “This is an opportunity for the SNP to right a wrong, an attack on the trade unions. I hope [the unions] call for a ballot to test the water. Industrial relations are at an all-time low and I think the long-term effect on services could be severe.”

Councillor John Mooney called the cuts last month a “breach of trust” and said it was a “very bad outcome for workers and members of the public”.

Discussions are to continue with the unions but a decision on how to proceed will be made by the corporate services committee regardless next month.

Labour leader Martin Rooney said: “The SNP promised the trade unions they would be on their side and be anti-austerity and they failed on both counts.”