Unison said its campaign against new terms and conditions at the local authority will continue, despite a U-turn telling workers to agree to them "under duress".
Branch chairwoman Lesley Russell last night said "further action" was planned, but would not be more specific.
Ms Russell added: "The campaign will continue."
The union and management at the council have been at loggerheads over a deal that Unison says cuts wages by 4.5% and makes its members work an hour extra a week.
Council chief executive Bob Jack said Unison had made a "major U-turn" by advising its workers to sign the deal.
He said: "Unison has been forced by its lawyers to change its advice to members and is now calling on them to sign up for the new terms and conditions. Unison's intemperate claims about 'savage cuts' are a long way from reality."