Unions said the offer of several hundred pounds to social workers and care staff at Glasgow City Council during a ballot for industrial action amounted to bribery and was urging its members to reject it.
Letters have been sent to about 1,200 workers providing residential care and emergency social work services, offering what the council describes as compensation for loss of earnings for giving up over half of the allocated public holidays where they are paid double.
But it warns that no payments will be made while the threat of industrial action still looms.
The reaction by the GMB union and Unison to the offer is likely to lead to a further deterioration in relations between sections of the workforce and the Labour administration, headed by former Scottish Executive minister Frank McAveety.
As well as the long-running issue of changes to terms and conditions across the workforce, the authority is already in a high-profile dispute with Unison over payments to school janitors employed by its arms-length company Cordia.
GMB Scotland officer Benny Rankin said: “We are now in a situation where Glasgow City Council is undertaking classic union busting tactics to undermine our industrial action ballot. It is totally unacceptable.
“Glasgow City Council is supposedly cash-strapped but they can find the funding to try and break support for strike action.
“How do they even begin to explain this to their low-paid workers facing the prospect of cuts to their incomes, never mind the taxpayers?”
Unison’s Brian Smith added: “The idea that the council is asking workers to sell their conditions for several hundred pounds is basically a bribe.
“But while they might get £800 just now, what do they lose out over a decade, up to £10,000 or £20,000 if they’ve 20 years’ service left.
“It’s a bribe to push staff towards selling the conditions they’ve fought hard for, for themselves and future workers.”
The loss of six public holidays is part of an overhaul plan by the council to save around £4.5 million by overhauling workforce terms and conditions.
The average offer for loss of payments is around a one-off £600, about a year’s public holiday overtime.
The staff affected are all under the umbrella of the newly created health and social care partnership (HSCP), the body jointly run by the council and the NHS.
The letter from one of the HSCP’s chief officers, Susanne Millar, says: “In making this change it is recognised that there is a loss of earnings for some staff in social work and the payment offered is a genuine attempt to mitigate against any loss.”
A council spokesman said: “Obviously, no-one can be paid compensation until agreement has been reached on the matter.
“We believe this is fair and reasonable, and hope the issue can be resolved soon to protect services for the public.”