Civil servants have staged a Budget day strike, hitting courts, government departments, museums and driving test centres in an escalation of a bitter dispute over pay, pensions and working conditions.
The Public and Commercial Services union said tens of thousands of its members joined the 24-hour walkout, which will be followed by a half-day strike on 5 April and other forms of industrial action.
Picket lines were mounted outside government offices, museums, galleries, the Houses of Parliament and the Office for National Statistics in London where the latest unemployment figures were published.
PCS members handed out leaflets which said the dispute was the most serious ever faced by the union.
"We must take action to force the Government to negotiate," said one of the pickets.
The union said the strike affected business in the Welsh Assembly, closed museums in parts of the country, hit government departments as well as border control areas at airports.
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The union has been embroiled in a long-running dispute with the government over pay and pensions, which worsened when the PCS accused ministers of attacking working conditions of civil servants.
PCS general secretary Mark Serwotka said: "What this strike shows is that PCS members are determined to show the government they will not be not forced to accept having their pay frozen, their terms and conditions slashed while the chancellor plots to increase the pain on the public sector with further cuts.
"The latest set of employment figures are the latest evidence that austerity isn't working and there is an alternative to cutting the living standards of hard-working public servants create jobs and growth.
"We are calling for meaningful talks on fundamental issues surrounding pay and terms and conditions and we hope the government gets the message loud and clear."
Cabinet Office minister Francis Maude, answering questions in the Commons, said fewer than 95,000 staff were on strike and had achieved only a "minimal impact" on services.
He told MPs: "The latest numbers suggest that fewer than 95,000 civil servants went on strike today.
"The leaders of the PCS, who are not serving their hard-working members at all well, claimed this morning that 250,000 civil servants were on strike. That was simply untrue, it is less than 95,000."
He added: "There has been minimal impact on public services. The public will have been inconvenienced to a very small extent by the strike today.
"The borders at the airports and ports have been properly manned, queues have been minimal and I am delighted to say that at Birmingham airport alone there have been significant seizures of illegal drugs, to the benefit of protecting the public."