Cabinet Office minister Francis Maude has called the PCS' decision to strike "futile, counter-productive and irresponsible."
He added that the decision to strike benefits no one, but "threatens the services people rely on."
He said: "I can reassure the public that the Government has done everything we can to minimise disruption [today]. Rigorous contingency planning is in place to try and limit the impact of the strike action and to ensure that affected public services operate as effectively as possible."
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A teenager who grew an incredible 10cm overnight after an operation to correct a curve in her spine has been given the all clear by doctors.
Severe weather warnings have been issued for northern England and Scotland, where it could drop to minus 10C (14F) in some places.
Expect it to feel colder with a biting, bitter windchill, this Valentine's Day.