Union leaders have called on Birmingham City Council to "pay women workers what they are owed" and drop an appeal against the recent equal pay judgment the authority lost.
In April, Birmingham Employment Tribunal ruled that the council was wrong to exclude 4,000 low-paid women, working as cleaners and care assistants, from bonuses paid to men.
Birmingham, which could be facing a payout of £600m, is appealing elements of the judgment, but Dave Prentis, Unison general secretary, today said the tribunal made clear that the council's defence "was fatally flawed".
"All Unison has ever wanted is fair and equal pay for women workers in the city," he said. "Birmingham City Council should stop now, drop the appeal and pay these women what they are entitled to."
A Birmingham City Council spokesman told Personnel Today the appeal has been lodged as "there are some elements of the judgment that we feel are incorrect".
"The tribunal case related to historical bonus schemes that were abolished in 2007 when the council undertook a review of its terms and conditions," he said. "The council has already settled 11,000 equal pay cases, and has always acted responsibly to any equal pay claim, and now has in place a revised pay and grading structure."
"An audit of this revised seven-grade pay structure was independently undertaken by (consultancy) TMS and it confirmed that it reduced overall gender pay gaps below the Equal Opportunities Commission significance level and they remain below the Equality and Human Rights Commission significance level," the spokesman added.
The latest spat comes after the GMB union claimed that relations between the council and trade unions were the "worst in the country".