The Government's hopes of resolving the bitter dispute over public sector pensions have received a fresh blow after the leaders of tens of thousands of council workers rejected a final offer.
Unite's national local authority committee turned down the proposed deal, saying "genuine discussions" should be held without "arbitrary" deadlines.
The move follows a similar decision last week by the union's health executive and a decision by the British Medical Association to survey around 130,000 doctors and medical students on the offer, raising the prospect of their first industrial action ballot for more than 30 years. The two biggest teaching unions also refused to sign up to the deal as they pressed for more talks.
Unite general secretary Len McCluskey said: "Unite's local authority representatives have lost trust after (Communities and local Government Secretary) Eric Pickles let the Government's real agenda out of the bag.
"The security of our members in retirement is just too important to leave any space for doubt or mistrust, so the union's senior representatives in local government have rejected the Government's proposals. There now needs to be genuine discussions without arbitrary deadlines. Our members need clarity before we can move forward."
Unite said a row before Christmas over a letter from Mr Pickles, raising the issue of an employer cost-ceiling on pension contributions, had caused a "crisis" of confidence and trust.
Leaders of the biggest public sector union, Unison, will meet on Wednesday to consider the final offer, while unions will hold talks at the TUC later this week to decide their next move.
Bob Neill, Minister for Local Government, said: "The decision by Unite is disappointing, but Unite only have 30,000 members in the Local Government Pension Scheme, out of a total active membership of 1.6 million.
"Our proposals represent a good deal for public sector workers and taxpayers. We need to put local government pensions on a sustainable and fair footing, and this is a generous offer. Town hall pensions now cost taxpayers £300 per household per year, and the cost has trebled since 1997. This is not fair on families and pensioners struggling to pay their council tax bills, and that is why this Government is committed to fair reforms."
Unite said the Government statement had "massively" under-estimated its membership, insisting it had 90,000 members in local government across the UK.