Unite said it would not take a new 5% pay offer to its members due to “insignificant detail”.
Bin strikes across Scottish local authorities are to continue as planned with no breakthrough in talks.
Rubbish has been piling up in Edinburgh where hundreds of GMB and Unite union members in the city’s waste and recycling service are striking.
Local authorities have increased their pay offer from 3.5% to 5%.
But Unite said it would not take the offer to its members due to “insignificant detail” about how it affects lowest paid workers.
The strike in Edinburgh is due to last for 12 days until 30 August – the day after the end of the city’s International and Fringe festivals.
It is the first in a series planned across Scotland.
Further strike action from workers in waste and recycling services is planned in the following councils:
Unite – 24 to 31 August Aberdeen, Angus, Clackmannanshire, Dundee, East Ayrshire, East Lothian, East Renfrewshire, Edinburgh, Falkirk, Glasgow, Highland, Inverclyde, South Ayrshire, South Lanarkshire and West Lothian.
Unison – August 26 to 29 and September 7 to 10 Aberdeenshire, Clackmannanshire, East Renfrewshire, Glasgow, Inverclyde, North Lanarkshire, Stirling and South Lanarkshire
GMB – August 26 to 29 and September 7 to 10 Aberdeen, Angus, Dundee, East Ayrshire, East Lothian, Falkirk, Glasgow, Inverclyde, Highland, Midlothian, Orkney, South Ayrshire, South Lanarkshire, West Lothian, Perth and Kinross, and North Lanarkshire.
Union members have rejected a pay offer equivalent to a 3.5% increase.
On Monday, following a meeting of Unite’s local government representatives committee, the union said it would not take the new 5% offer to members.
Alison Maclean, Unite industrial officer, said: “Unite’s local government committee has reaffirmed that the strike action ongoing in Edinburgh and scheduled to take place in a further 14 councils continues as planned.
“There remains insignificant detail on the 5% pay offer, and what this in reality means for the lowest paid workers.
“At this moment the offer from Cosla remains a vague aspirational pledge but Unite can’t take anything to our wider membership unless we have specifics and guarantees.”
The union said it was going to meet with Cosla on Tuesday and reassess the situation.
Nicola Sturgeon previously said council leaders should make a 5% pay offer to staff to avert further strikes.