The biggest civil service union today threatened another strike in protest at the Government's controversial pension reforms amid claims that the coalition "unleashed hell" against workers and communities through its spending cuts.
The Public and Commercial Services union agreed to build towards fresh walkouts at the end of next month with as many unions as possible unless talks over the pension changes are reopened.
Delegates at the PCS's annual conference in Brighton also vowed to campaign against legislation which will enable the pension reforms to take place.
General secretary Mark Serwotka said workers faced "unprecedented" challenges, adding: "What the Government is doing is unleashing hell on members, their communities and vulnerable families.
"This is a Government of millionaires, of incompetence, which is ruling on behalf of a tiny elite, without a mandate."
Mr Serwotka said unions were now the real opposition to the Government, attacking Labour for going along with many of the coalition's cuts.
Some delegates argued that the PCS should go it alone with further walkouts if other unions decided against taking further action.
But Mr Serwotka said PCS members had voted to take industrial action alongside other unions, so some would feel demoralised if that did not happen.
"Let us hope we have a massive strike in June, but it needs to be with other unions."
The union has already taken part in three days of national strikes over pensions and is planning further action in some Government departments, including transport.
Mr Serwotka told the 1,000 delegates that Cabinet Office Minister Francis Maude was refusing to reopen talks, describing him as the "Minister for Chaos" following the row over petrol supplies when tanker drivers threatened to strike.
Thousands of PCS members in the Department for Transport are set to take industrial action soon in a row over job cuts and privatisation, hitting driving tests and issuing of licences.
The union is also balloting its members in HM Revenue and Customs for strikes over similar issues.
Mr Serwotka said it was clear from today's conference discussion that PCS members wanted to continue fighting the Government's pension changes, which would still mean that public servants would work longer, pay more into their pensions and receive less in retirement.
"There was complete unity that we are right to fight on, and the stakes are massive."
He said he will now contact the unions which took part in the strike on May 10 to discuss the prospect of another walkout in June.
Teaching unions will not join any action next month, but Mr Serwotka said the campaign will continue into the autumn, echoing warnings from Unite leader Len McCluskey that strikes could be held into next year.
"Action will ebb and flow, but the common link is opposition to the effects of the austerity cuts, and the potential for other unions to rejoin the fight.
"There were representatives from a number of Government departments here and no-one wants to give up, which I think is significant.
"We have not had any move from the Government on the three questions of retiring later, increased pension contributions and receiving less, and the worry is that things will get worse."
Mr Maude said: "Once again I am disappointed that the PCS insists on pushing for futile strike action which benefits no-one, and I would urge them to reconsider their position.
"As we have said time and again, pension talks will not be reopened and nothing further will be achieved through strike action.
"In March we set out our final proposed agreements on pension reform following more than a year of intensive discussions with trades unions.
"Our reforms ensure that public sector pensions will remain among the very best available and that they can be sustained for the future.
"Public sector workers are being asked to work a bit longer and pay a bit more, but they will continue to get a guaranteed pension which is index-linked and inflation-proofed.
"Most staff on low and middle incomes will receive a pension at retirement as good as what they expect today, and for many it will be even better."