Hundreds of thousands of workers across the UK were taking part in the action, with up to 30,000 members of the Public and Commercial Services union in Scotland said to be downing tools.

There were picket lines outside jobcentres, tax offices, courts and the Scottish Government offices also among the sites affected.

Cabinet Office minister Francis Maude has described the strike as "futile" and insisted that talks over pensions will not be reopened.

But PCS Scottish secretary Lynn Henderson said the union would get back round the negotiating table "as soon as the Government are ready to meet with us".

Today prison officers across Scotland have joined a strike of public sector workers protesting about pensions.

The staff walked out despite a voluntary deal the Prison Officers Association has with the Scottish Prison Service not to strike.

It is illegal for prison officers in England and Wales to strike, but not in Scotland.

A spokesman for the Scottish Prison Service today said: "The strike is widespread, staff at most of our prisons are taking part, with the exception of Kilmarnock and Addiewell."

Up to 400,000 public sector workers are expected to join the 24-hour UK-wide walkout.

There is widespread support for public sector workers who have taken action, union leaders said.

In Scotland, the Public and Commercial Services Union said its 30,000 members would be taking part in the strike.

It said there would be picket lines throughout the day at job centres, tax offices, Scottish government offices, the Scottish Parliament, Faslane nuclear base and both Edinburgh and Stirling Castle.

A lunchtime rally was scheduled at Glasgow Royal Concert Hall.

Other workers expected to join the strike include border agency staff, lecturers, health visitors, pharmacists and paramedics.

There were also be picket lines mounted at the Scottish Parliament, Faslane nuclear base and both Edinburgh and Stirling Castle.

A spokesman for Glasgow Airport, said: "We have worked closely with UKBA staff in the run up to today's strike and have a contingency plan in place."

Lynn Henderson, PCS Scottish secretary said: "This strike is part of a national co-ordinated campaign in defence of public sector pensions. Scottish public sector workers are suffering pension losses, at the same time as their pay is being frozen for a second year by Scottish and UK governments."

Scottish Greens are backing members striking by refusing to cross the picket line at Holyrood.

Green co-leader Patrick Harvie MSP said: "Public sector pensions are affordable and sustainable. It's not a great surprise these workers are being attacked by David Cameron and his well-off coalition cronies. But the lack of backbone being shown by the SNP and Labour is baffling."

The walkout follows last November's huge stoppage by more than one-and-a-half million workers across the UK in protest at the changes to their pensions.