Workers at council recycling centres in Sheffield have called indefinite strike action from Saturday, according to local reports.
The employees of SOVA Recycling, who run household waste recycling centres for Veolia and Sheffield City Council, are resisting council plans to close some of the sites on week days.
Seven jobs are threatened by the cost-cutting plan which the council says will save £500,000.
The workers have already staged a series of strikes and say an indefinite walk-out will begin from Saturday unless an agreement is reached.
Pete Davies, an official for the GMB, told the BBC: “We need a complete re-think on the closure of these sites.”
He added that the union was committed to “keep this battle going”, but said he was optimistic a meeting would be held with the council to resolve the issue.
Jack Scott, cabinet member for environment and recycling at Sheffield council, told the BBC: “It’s disappointing we’re in this position.
“We are keen to find any options we can discuss, and look at new ways of working and also re-build some trust which might have been lost.
“We want to keep talking. We have very different perspectives on this and we’re quite a distance apart.”