Unite has rejected the flat rate pay rise offered to all council staff this week.
Employers have put forward a flat rate pay rise of £1,925, saying this would give the lowest paid workers a double digit pay increase.
However, Unite has rejected the offer arguing it represents a cut in real terms.
Sharon Graham, Unite general secretary, said: 'Most local government workers are being offered yet another pay cut masquerading as a pay increase.
'Council workers have seen their rates of pay massively eroded for over a decade through pay freezes and below inflation increases. Highly skilled and experienced workers are leaving the sector in droves as they are undervalued and struggling to make ends meet.
'Council leaders need to stop ducking the issue and make an offer that both meets members’ expectations and which starts to tackle the decade plus decline in council workers’ pay.'
The union warned it would consider all options in how to escalate the dispute if an improved offer is not made.