A union is urging employees not to sign any equal pay settlement offers from Birmingham City Council after claiming that "significant" new information has emerged surrounding problems with the local authority's job evaluation scheme.
GMB union, which has 7,000 members working within the local authority, said the action resulted from the council saying in an employment tribunal that key roles had been evaluated wrongly and its interpretation of the National Joint Council scheme could not be relied upon.
Unions had previously negotiated a Memorandum of Understanding (MOU) with the council for payments to go to staff to ensure parity with colleagues who had received settlement through no-win, no-fee lawyers.
However, the council's evidence now brings into question the validity of the MOU and the true value of settlements about to be offered to thousands of council workers, the union said.
GMB announced it is now undertaking an immediate review of all possible equal pay cases at the city council.
GMB is considering legal proceedings and industrial action.
A reported £1.25 billion in equal pay settlements have been paid out by the local authority over the last decade, according to GMB.
Michelle McCrossen, GMB Organiser, claimed it looks "increasingly clear" that Birmingham City Council faces another equal pay crisis.
McCrossen said: "The council's admission that their job evaluation system can't be relied upon renders useless the previous Memorandum of Understanding between the council and unions, and its flawed grading of equivalent roles also suggests the council has been acting in bad faith throughout this process.
"It's unacceptable and that's why we are now urging our members: Do not sign any settlement offer the council may make to you over the coming days. There is a real danger that if members sign these offers, they will be waiving their rights to a full and proper settlement.
"GMB will now start lodging new equal pay claims on behalf of members who we believe are being discriminated against by the council, and we will be aggressive in our pursuit of pay justice."
A council spokesperson said: "The council is committed to treating all members of staff fairly and committed to resolving any outstanding matters around equal pay once and for all."