Staff have already held two strikes over the pay dispute

Members of the biggest civil service union, the Public and Commercial Services Union, voted to hold two days of strikes, possibly in July.

A major lobby of parliament will also be held on 14 July, the union's annual conference decided on Monday.

The staff have already staged two 48-hour strikes in protest at a new scheme linking pay to performance.

Union activists had been confident the emergency motion would be accepted by delegates, following strikes in February and April by the union's 90,000 members at the Department for Work and Pensions.

'Furious' members

The motion had condemned the department for the pay scheme.

Union spokesman Alex Flynn said: "There is a real fear that management will impose the pay settlement for 2004. This would be yet another arrogant and unacceptable step."

National officer Keith Wylie said workers were "furious" that last year's pay deal had been imposed without agreement and that the "unfair" performance development scheme (DPS) was now in place.

Department workers earn about �3,000 a year less than their counterparts in other government departments and were seeing their pay and pensions determined by an unfair performance regime, he added.

He said that 28 department staff, including many line managers, had now been suspended without pay for refusing to co-operate with the performance scheme.

Suspensions have taken place across the country, including Sheffield, Leeds, London and parts of Scotland.

Staff rewards

A union insider said people were angry at the arrogant way senior managers had approached pay and were now dragging their feet over wage rises due next month, BBC labour affairs correspondent Stephen Cape said.

A spokeswoman for the department defended the scheme, saying it had been introduced to boost performance and reward staff for their contribution.

Further stoppages would disrupt Job Centres and Benefit Offices if the tens of thousands of staff went on strike.

The strike in April contributed to the biggest civil service disruption in 13 years, when thousands of staff at several government departments co-ordinated their industrial action.