The warning came from Paul Noon, General Secretary of the Prospect union, representing 102,000 specialists and managers in the public and private sectors.

“The patience of our members in the public sector has been stretched to breaking point. Someone, somewhere in government is going to have to wake up and smell the coffee and realise why it is that public sector workers have turned against the government at the ballot box.”

In his keynote address to the Prospect national conference in Torquay, Noon said: “The promise of year-on-year pay cuts for our civil service members is not the best way of securing their support for the government’s programme or indeed their electoral support.

“One of the key principles of public sector pay should be fairness to public servants as well as the taxpayer. This is simply not happening and ultimately will damage public services as well as being unjust to public servants.”

Accusing the government of “being in a mess”, Noon said it was deeply depressing that privatisation policies initiated under a Conservative administration were continuing under a Labour government.

He said the union had opened up discussions with the Conservative opposition and talks with their trade union envoy Richard Balfe were scheduled to begin within the next month.

He acknowledged fears for the future of public service pensions under a Conservative administration, and for continued government funding to modernise trade union structures and promote union learning at the workplace.

But, he said, it was better to face up to those issues and argue them out in talks with the Conservative party before a general election rather than after.