Details have emerged of a major compromise over plans to remove unsocial hours payments and other wage perks from 26,000 Birmingham City Council employees

It is seen as a sign that the authority’s Conservative-Liberal Democrat leadership is actively seeking to avoid damaging industrial action.

Human Resources cabinet member Alan Rudge chose a private scrutiny committee meeting to reveal a sweetener for the unions.

He promised that major changes to working conditions, known as the Birmingham Contract, will not now be introduced until October and are likely to be accompanied by an 18-month pay protection plan for lower paid workers guaranteeing that no-one will lose more than 10 per cent of their salary.

But his compromise did not impress the trade union Unison, which is pressing ahead with balloting members on possible industrial action.

Unison assistant general secretary Roger McKenzie said: “Birmingham City Council workers are rightly angry at the council’s contemptuous Birmingham Contract.”

Mr McKenzie described Coun Rudge’s concessions as “a step in the right direction”, but said the ballot would still be held.

He added: “I call on the council to sit down with the trade unions and work with us to reach a truly fair settlement.”

Coun Rudge (Con, Sutton Vesey) revealed details of his offer while being quizzed by councillors about the impact of the Birmingham Contract, which will cut the council wage bill by almost £10 million a year.

His intervention did not prevent the committee from “calling in” a report on the new contract, forcing the council cabinet to reconsider the matter and raising a question over whether this can be done before the city’s crucial budget-fixing meeting on March 1.

The changes, covering all of the non-schools workforce, will end a 50-year-old system of enhanced shift payments for night and weekend working, scrap free car parking spaces for hundreds of managers, and allow staff to be sent to work in any department or office without receiving a disturbance allowance.

But there will be no concessions on planned changes to the working conditions of about 600 council bin men and street sweepers.

Cabinet transportation member Coun Tim Huxtable (Con Bournville) signalled his intention to impose new contracts on the workforce, ending overtime payments and saving about £16 million a year by 2015.

Opposition Labour councillors fear the Conservative-Liberal Democrat coalition’s determination to face down the bin men could lead to more industrial action, with a repeat of the chaos over Christmas and the New Year when bags of rubbish lay uncollected on the streets for up to a month.

Attempts by Labour to debate the Birmingham Contract in open session failed after council lawyers said the subject was too sensitive to discuss in public.

Labour human resources spokesman Steve Bedser said he couldn’t understand why the meeting should have been held in private.

Details of the proposed changes were already in the public domain and 25,000 workers “know full well what is going on”, he added.