More than 90,000 council and school workers in Scotland will be balloted for strike action in a pay dispute, a union has said.

Unison has rejected the latest pay offer from local government umbrella body Cosla of an hourly increase of 67p or 3.6%, whichever is higher.

On Friday, council leaders voted to impose the deal despite Unison’s opposition, saying GMB and Unite members have accepted it.

Council leaders argue the deal is “at the absolute limit of affordability” given the tight financial situation.

Unison Scotland’s local government lead David O’Connor said: “To say this is a bitter disappointment is an understatement.

“Just two days ago, Cosla’s lead negotiator councillor Katie Hagmann and the Cabinet Secretary for Local Government and Finance Shona Robison MSP assured the union they were committed to a negotiated settlement.

“Now, they’ve resorted to some of the worst employment practices by imposing this deal.

“They should be utterly ashamed of themselves.

“It’s both upsetting and infuriating to see that they’re once again so undervalued.

“Politicians have enjoyed pay rises upwards of 6.7%, but they’re telling dedicated workers to limit their expectations.”

Cosla’s resource spokeswoman Ms Hagmann said: “We are disappointed that Unison have not agreed the current good pay offer from Cosla.

“Leaders made the decision to implement the offer because it was clear after further discussions this week that there was no additional funding available from within local government or from Scottish Government.

“Taking account of that, leaders decided it was important to get the pay uplift into worker’s pockets without delay.

“The decision to implement does not end the negotiation and we are keen that the talks can be concluded by agreement.

“We are concerned by the threats of industrial action which is in the interests of no one and will place vulnerable service users at risk and inconvenience citizens across our communities.

“This reaction from Unison is disappointing considering that the offer is well above the rate of inflation and aligns exactly with the pay requests of all Trade Unions made in their letter of July 31.

“The pay offer is worth an average 4.27% which is the same value as that accepted by our teaching negotiation group and the same value for all other Local Government workers.

“We respect all our unions for their important work in protecting their members best interests.

“Nonetheless we urge Unison not to progress with this damaging industrial action. (The offer) is at the absolute limit of affordability in the extremely challenging financial context we face.”

Finance Secretary Ms Robison said: “The decision made by council leaders to implement the local government pay offer will halt any further delays and get pay in the pockets of valued workers – including those who need it most – before Christmas.

“While this Government fully respects the decision by Unison members to reject the offer, no-one’s interests will be served by industrial action.

“I hope that Unison members recognise the strength of this offer which has already been accepted by GMB and Unite.

“The pay offer is better than that made to local government workers in the rest of the UK.

“It will see the lowest-paid workers, including Unison members, receive a 5.63% pay increase and most local government workers receive more than 4%.

“This delivers what GMB, Unite and Unison asked for from councils at the end of July.

“The Scottish Government has provided £77.5 million to support this offer and I confirmed to Cosla and unions when we met that we have utilised all available funding to support local government pay.

“Although the Scottish Government has no formal role in these negotiations, I know that Cosla remains committed to the negotiation process with an ambition to reach a collective agreement with all three unions if possible.”