Glasgow City Council is to sack more than 23,000 members of staff and then rehire them to new contracts after pay talks broke down with unions.

The local authority says letters will be sent to its non-teaching staff next week, with new contracts then taking effect from 1 January.

Talks earlier this week between the council and the GMB, Unison and Unite unions fell apart on Wednesday when Unison said it would not ballot its members on a proposed new pay offer.

The negotiations concerned plans by the council to implement a new pay and grading system, to replace one that was found to discriminate against mostly women workers. However the move meant 11% of employees would see wages cut.

The council said redundancy notices would be withdrawn if the three unions agreed to ballot their members on the pay offer.

The letters of dismissal will cover every member of non-teaching staff on the council’s books, including chief executive Susanne Millar, nursery staff and refuse collectors.

Unions called the move a “scandalous threat” and demanded it be withdrawn.

In a statement, the council’s director of communications and corporate governance Colin Edgar claimed Unison had betrayed its own members by not balloting them.

He said talks breaking down meant there was now “no agreed way forward between the council and the joint trade unions”.

“The council has gone as far as it can,” said Edgar. “The new pay and grading scheme removes unequal pay and sees pay rise or stay the same for 90% of staff – the council’s total pay bill will be substantially higher.

“For those staff who are in detriment our joint trade unions negotiated an increase in pay protection from six months to 12 months.

“Additionally, some trade unions are devoting energy to local consultations to mitigate the impact on those colleagues in detriment – focusing on providing specific solutions.”

Edgar said council officials hoped to meet with Unison earlier but the union had not attended the meeting.

He added: “The offer which has been unilaterally rejected by Unison would have taken dismissals off the table and seen additional cash for those members of staff, and members of all unions, who are due back pay.

“It beggars belief that they would betray their own members in this way.”

Unison Scotland regional organiser Mandy McDowall said: “Glasgow City Council staff are not going to be bounced into a shoddy deal by bosses trying to bully them with arbitrary deadlines.

“The council’s decision to dismiss workers helps nobody and Glasgow City Council risks being labelled a pariah employer if it refuses to negotiate in good faith with its staff.”

She added Unison would continue to work to secure a fair deal and would ballot its members on an offer once discussions had finished.

Graham McNabb, an industrial officer with Unite the Union, said: “Glasgow City Council must remove direct threats to our membership in its proposed new pay and grading structure, whether it is through cuts to terms and conditions, or the scandalous threat of fire and rehire tactics.

“If they go down this reckless path then it will be met with the full force of Unite.”

At a meeting last month, the council agreed to an overhaul of its pay and grading structure after eight years of negotiations.

The new system would see 63% of those affected gain financially while 11% will have their wages reduced.

The highest drop in wages is expected to be around £11,500.

The GMB and Unite had earlier said they secured an additional £110m into the funding package to resolve key issues affecting “the vast majority of our members”.

The two unions sent out a message to staff earlier warning the fire and rehire policy might be introduced, and saying the extra money was now “hanging by a thread.”

However Unison said this extra funding would go towards towards “assimilation and arrears”, and not help the staff facing wage cuts.

GMB and Unite both wanted the council to table the offer so members could make a decision.

Both unions stated that if the council pursues the fire and rehire policy then they will “immediately enter into dispute to secure the improved package and halt fire and rehire”.

A letter to members of GMB and Unite, sent before the council announced it was implementing the policy, stated fire and re-hire would be a “self-defeating step” by the local authority.

It added that such a move would “hasten a prolonged industrial dispute” between unions and the council.

The letters sent to staff say their new contracts would begin the day after the old ones would end, and that continuity of service would not be affected.

Glasgow City Council has been embroiled in problems over pay for years.

The local authority previously paid out about £770m after it emerged female workers in roles such as catering or cleaning had for years been receiving up to £3 an hour less than those in male-dominated areas such as refuse collection.

The new job evaluation scheme was designed to draw a line under the row by bringing pay scales into line with equality law, but it also meant some staff would face wage cuts, depending on what pay banding the new scheme placed them in.

This is a major escalation of the row over the proposed new pay structure at Glasgow City Council.

So-called “fire and rehire” tactics are always controversial. Unions often associate them with private sector companies seeking cuts – not major public sector employers.

Glasgow City Council had previously said it would explore mitigations for the 11% of staff facing a pay cut.

If the unions agree to ballot their members on the pay structure, the threat of “fire and rehire” will be withdrawn.

It is worth stressing that nobody is simply facing the sack as such. However anyone who did not sign a new contract would not have a job. Someone facing a pay cut may attempt to claim constructive dismissal.

Unions are likely to fight Glasgow City Council’s plan vigorously. Industrial action cannot be ruled out if there is no amicable settlement.