A senior union leader has warned of co-ordinated strikes by up to five million workers, including nurses, teachers, firefighters and civil servants.

They would strike over plans to increase the public sector pension age.

Speaking at the annual conference at the Brighton Centre, Mark Serwotka, general secretary of the Public and Commercial Services Union (PCSU), said workers were right to be sceptical about a pre-election pledge given by ministers to hold fresh talks over the dispute.

The move headed off a planned walk-out by more than one million workers in March.

Mr Serwotka told delegates in Brighton that if the development proved to be a pre-election "manoeuvre", he would work to mobilise 30 trade unions, representing five million workers, against plans to extend the pension age by five years to 65.

Mr Serwotka said there were "many battles" on the horizon for civil servants over pensions and over opposition to 100,000 job cuts.

The union has warned of a national strike if anyone is made compulsorily redundant and there could be industrial action across London in the next few weeks.

Mr Serwotka said thousands of union members in the capital were being balloted in protest at job losses in the Department For Work and Pensions. Any action could be followed by local stoppages, hitting benefit and pensions offices and job centres.

The Government was given a strong warning of "stormy waters" ahead by Mr Serwotka, who said there was an incredible amount of scepticism among workers about the Government's offer of talks over pensions.

Unions also did not accept pensions was a crisis which could not be resolved, given that the Chancellor had said the Government would spend "whatever it takes" on the war in Iraq, said Mr Serwotka.