Unions representing about 500,000 civil servants are to submit a joint pay claim for the first time.
The Public and Commercial Services union (PCS) and the Prospect union claim the present system is unfair and means there are more than 200 separate sets of pay negotiations across the Civil Service.
They want one national agreement to set minimum standards, including ensuring no-one earns less than £13,500 a year.
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The unions have also expressed concern about a growing disparity between the pay of some men and women.
The move comes just weeks after one million civil servants threatened to walk out over government plans to raise the public sector pension age from 60 to 65.
