Mark Serwotka, general secretary of the Public and Commercial Services Union, told its annual conference in Brighton yesterday that if the government did not back down over raising the compulsory pension age from 60 to 65 for all public sector workers, coordinated industrial action would be taken by trade unions.

He disclosed that the union was not only coordinating the potential industrial action with two other civil service unions, Prospect and the FDA, but planned to work with unions representing firefighters, the health service and local government.

The TUC has been asked to coordinate union negotiations over pensions with the aim of persuading the government to agree to concessions or to a much more flexible package for civil servants and other workers.

Mr Serwotka said: "We are hoping for the best, but we are preparing for the worst."

He added that the government needed to deliver on its promise of a fresh start for negotiations or else face the prospect of 30 unions uniting to oppose a compulsory higher retirement age.

Mr Serwotka's comments effectively end a general election truce agreed between the unions and the government. Before the election campaign, Tony Blair instructed cabinet colleagues to pull back from imposing a higher retirement age of 65 for local government and workers in Whitehall.

This decision stopped a series of one-day strikes that would have disrupted the election campaign.

The new worry for ministers is that the NHS, local government, Whitehall and the education service will be hit by a new series of one-day walkouts.

Mr Serwotka laid down the terms under which his 330,000 mainly low-paid civil servants would want to avoid industrial action. He insisted that the government retains both the final salary scheme for civil servants and introduces a new "career average" salary scheme for those who want to opt out of the final salary scheme.

The union also warned that it will take industrial action if the government introduces compulsory redundancies as part of its plan to shed 84,000 civil service jobs.

Mr Serwotka said: "The fear is of yet more outsourcing and more privatisation hitting services we all rely on. Key government reforms are in real danger of failing and large sections of the government's own workforce, faced with growing job insecurity and continuing low pay, are on the verge of losing confidence in the government as an employer." He also attacked Kevin White, director of human resources at the Department for Works and Pensions, for deliberately proposing a special pensions deal for the most highly paid civil servants, worth hundreds of thousands of pounds a year. Mr White had no idea of the poor conditions his workers had to suffer, said Mr Serwotka.