Birmingham City Council today said that 16,000 employees will be assumed to have accepted new contracts and a controversial pay scheme if they turn up to work on Monday.
The single status pay and grading changes are due to come into effect on Monday, leaving thousands of workers facing pay cuts.
Some 40 per cent of the workforce - about 16,000 - have refused to sign the contracts and trade unions are threatening new strikes on top of a one-day stoppage that took place at the beginning of last month.
But council human resources director Andy Albon has written to all 40,000 employees affected by the pay and grading structure telling them: "If you attend work as normal on March 31 you will be subject to the terms and conditions laid down in your new contract regardless of whether or not you have voluntarily accepted the offer."
Human resources cabinet member Alan Rudge, the politician responsible for pushing through single status, is challenging the unions to put a revised pay and grading offer to a formal ballot.
He said a series of mass meetings held earlier this month, where union members overwhelmingly rejected the package by a show of hands, had "no validity whatsoever".
Coun Rudge (Con Sutton Vesey) believed the meetings were infiltrated by "extremists", including members of the Socialist Workers’ Party, who may not have been union members.
He added: "We don’t even know who was there. Anyone could have been there. The maximum number of people who could have attended those meetings would only amount to about 10 per cent of the total union membership.
"The rules say they must put this to a proper ballot and that is what I would expect to happen."
He described the revised offer as one of the best single status deals anywhere in the country with one of the smallest proportions of staff set to suffer pay cuts of any large city council.
Almost 60 per cent of council employees have accepted the new contracts. Those who are refusing to do so are acting on union advice that by signing the documents they risk damaging any case for compensation that might be put to an employment tribunal at a later date.
The improved pay and grading offer was finalised on March 12 following two weeks of intensive talks between Coun Rudge and the unions.
Under the proposals, the council offered to:
* Increase the number of staff receiving pay increases to 48 per cent of the workforce.
* Extend protection of basic pay for staff suffering a reduction in salary to March 2011.
* Work to reduce the number of staff facing a pay cut to about 1,400 at the end of the protection period.
Ian Jones, of Birmingham employment law solicitors Spencer Shaw, said the pay and grading review was a "legal minefield".
He warned that any council employee not turning up for work on Monday could be deemed by the local authority to have resigned. But that might lead to workers taking legal action against the council for unlawful dismissal.
Anyone turning up for work, and continuing to work to the new contract for a period of several months, could be deemed by the council to have accepted the changed conditions, Mr Jones added.
It was also possible that employees whose working conditions were radically changed could claim constructive dismissal and sue the council for compensation.
The unions insist they do not have to carry out a further ballot to call more strikes because they already have a legal mandate for industrial action.
The sole strike held so far saw about 9,000 workers stay at home out of a union membership of about 20,000, closing scores of schools and severely disrupting refuse collections.
Steve Foster, chairman of the joint trade union negotiating committee, revealed last week that dates in April were being considered for further stoppages. It is understood that three dates have been pencilled in for one-day strikes.
Mr Foster said union members were unhappy about proposals for performance related pay and the fact that new joiners could be earning less than the people they are working alongside.