Civil servants working in more than 200 government departments and agencies have voted to go on strike over planned job cuts.
Members of the Public and Commercial Services (PCS) union voted 61 per cent in favour of industrial action on January 31st, followed by a two-week ban on overtime.
The Cabinet Office said the strike was unnecessary, but PCS general secretary Mark Serwotka said it showed the "depth of anger" against the government's efforts to implement the Gershon efficiency savings.
With more than 325,000 members, the PCS is the UK's sixth largest union. It has previously staged a series of isolated strikes, but today's ballot - which recorded a turnout of 38 per cent - would see members stay out en bloc.
The strike is planned to coincide with the deadline for self-assessment tax returns and is likely to hit HM Revenue and Customs the most. Further action could be in the offing, whether right across the civil service or in specific departments.
"Patience has worn thin with services suffering as a result of job cuts, billions being spent on private sector consultants and some of the lowest paid facing a pay cut in real terms," Mr Serwotka said.
He warned: "If the government are going to avoid ongoing industrial action...then they need to give assurances over jobs, services and privatisation as well as making serious headway in tackling pay inequalities and low pay in the civil service and related bodies."
However, Cabinet Office minister Pat McFadden said: "There is no need for strike action. The government values the civil service highly. If PCS members have concerns about job losses or pay there is an established industrial relations process to discuss these issues.
"The PCS are the only civil service union to have balloted for strike action. We will do everything we can to avoid compulsory redundancies but cannot give guarantees it will never happen throughout the efficiency savings (Gershon) process."
Peter Gershon was charged with identifying government savings in August 2003, and in July the following year published plans to save £20 billion by 2007-08 by cutting down on bureaucracy and inefficiency. The proposals include cutting 84,000 civil service jobs.