Birmingham City Council is to seek a court injunction against striking refuse workers unless an arbitration is successful.
The move has led union Unite to threaten an all-out strike, and has provoked the resignation of Majid Mahmood as cabinet member for clean streets, waste and recycling.
He stepped down following a cabinet committee meeting on 15 January in protest about the threat of an injunction.
Mahmood said in a tweet: “I will not be a party to using Tory legislation to attack our trade union comrades. This goes against the very fabric of my socialist principles. I was elected by citizens on a UK Labour platform of equality, justice and fairness.”
Unite began its latest round of working to rule earlier this month in protest at part of the settlement of the 2017 refuse dispute, under which members of the GMB union received payments while those of Unite did not. A third union, Unison, is also taking industrial action.
Ian Ward, leader of the Labour-run council, said: “The people of Birmingham want us to resolve the waste collection dispute as quickly as possible and cabinet members agreed a way forward…but unfortunately councillor Mahmood changed his mind and was subsequently unwilling to support that way forward.
“Our focus now is to test our legal advice and seek a resolution to this dispute through binding arbitration at Acas.”
A report for Birmingham’s cabinet said the council “does not in any way agree with Unite’s position” that its members should receive the same payments made to those in the GMB, who were compensated for their union being excluded from the 2017 strike settlement talks. The council said this exclusion happened “at Unite’s insistence”.
The report said the council would invite Unite and Unison to discuss binding arbitration but would simultaneously “commence the legal process for a court application with a view to preventing unlawful industrial action”.
Birmingham estimated the legal cost of seeking an injunction at some £1.5m, but said this must be “balanced against ongoing costs of strike at a likely cost of £350,000 per week”.
The council admitted that since the work to rule began, it had dropped an average of 20 collection rounds a day and daily complaints about missed collections had increased from 214 to 1,030.
Unite warned it would escalate its action to a full strike action unless the council reversed its decision.
Assistant general secretary Howard Beckett said: “We had been led to believe that we would be heading to the conciliation service Acas…to discuss an offer from the council to resolve the dispute.
“Instead, it appears that the council wants to stand by the outrageous and immoral payments made to those who did not take industrial action in 2017 at the expense of those who took action to protect terms and conditions.”