Media playback is unsupported on your device Media caption The BBC's Lynda Hardy reports on the public sector march in London

Hundreds of thousands of public sector workers are taking part in a 24-hour UK-wide strike in a dispute with the government over pension changes.

The government says current pension schemes are unfair - and unaffordable because people are living longer.

But the unions say members are being "robbed" and will have to pay more and work longer for lower pensions.

Meanwhile, walkouts by prison service staff in England, Wales and Scotland have now ended.

Among the public sector workers taking part in the 24-hour strike are civil servants, NHS workers - including paramedics - border force staff and lecturers.

Around 32,000 police officers took part in a protest march against cuts, according to Metropolitan Police estimates.

Union leaders say up to 400,000 workers are on strike, while Cabinet Office Minister Francis Maude puts the total number of public sector workers who joined strikes at "close to 150,000" which includes 102,244 civil servants.

Mr Maude also said pension talks will not be reopened and "nothing further will be achieved through strike action", adding that it is "now time that union leaders put the best interests of their members first by asking them to accept our generous offer".

Mark Serwotka, general secretary of the PCS union - which estimates that an "overwhelming majority" of its 250,000 public sector members are on strike - said the UK would have "the highest pension age of any European country".

At the scene Protesters gathering this morning at St Thomas's Hospital in central London were in a great mood, sharing boxes of croissants and cheering to the horns of passing cars. Representatives from Unite took to the loudhailer, chanting about pensions and encouraging other unions to join them. It was a blustery but colourful scene with red flags fluttering in front of the hospital - most protesters were from the NHS. One man with a guitar sang a song. And as the crowd grew, the noise level grew. Lots of people expressed their anger and frustration at cuts to the NHS, to pensions and called for further strikes. Police looked on. "We're not expecting any trouble," said one. Eventually, when there were at least 350 people gathered, the crowd moved off over Westminster Bridge. Reaction to public sector strikes In pictures: Public sector strike

He added: "We're going to be paying more money when the cost of pensions are falling and our members have had a pay freeze for two years. So it's unfair, and ministers cannot justify the changes."

The government plans to raise the retirement age in line with the state pension age - eventually to rise to 68.

But Conservative Party chairman Lady Warsi told BBC News that workers were being asked to "to work a little bit longer and to pay a bit more, but they will be guaranteed a pension which is index-linked and inflation proof".

Strike action includes:

Business hit at the Welsh Assembly as Labour and Plaid Cymru members refuse to cross picket lines while National Museum for Wales closed to public, PCS says

About 5,000 NHS workers on strike in Wales with patients facing delays rather than cancellation, the BBC's Hywel Griffith says

Work on Royal Fleet Auxiliary ships in port in Birkenhead and Portland halted, according to the Rail Maritime and Transport union

Seven national museums as well as Tate Gallery closed in Liverpool, PCS says

Picket line outside the HQ of Maritime and Coastguard Agency in Southampton

30,000 PCS members striking in Scotland, the union says, with picket lines at job centres, tax offices, Scottish government offices, the Scottish Parliament, Faslane nuclear base and both Edinburgh and Stirling Castles

A murder trial jury was sent home at Mold Crown Court in Flintshire after the judge said the two defendants could not be brought to court because of action by prison officers

Media playback is unsupported on your device Media caption General Secretary of the PCS, Mark Serwotka, said the changes to pensions are ''unfair''

The Cabinet Office says UK border controls have been managed "without delays".

The Prison Officers Association (POA) instructed its members to provide only minimum cover to preserve health and safety within jails in England and Wales from 07:00 BST on Thursday.

The Ministry of Justice warned that it faced a possible injunction against its actions, but by mid-afternoon the union instructed its members to return to work. It also says 80% of its members at jails in England, Wales and Scotland took part.

The POA says the nationwide protests by its officers "achieved their objective in sending clear message to government that prison officers should not be working until the age of 68" and that their return to work was not prompted by the threat of an injunction.

The union's general secretary, Steve Gillan, also said it was not ruling out further action in future.

'Ultimate public service'

Government proposals to be considered in Parliament - as featured in the Public Service Pensions Bill detailed in the Queen's Speech on Wednesday - seek substantially increased employee contributions.

Thursday's protest is to all intents and purposes a traditional piece of industrial action, albeit by people who cannot withdraw their labour

As well as increasing the retirement age, the government also proposes that final-salary schemes will eventually be replaced by less generous career-average schemes.

In a central London march, thousands of off-duty officers took part in the biggest police rally since a 2008 protest against a pay award imposed by the Labour government.

Organiser the Police Federation said its members - who are prevented by law from taking industrial action - were protesting against a reduction in the number of officers, a lack of consultation over plans for reform, and pay and pensions.

The federation's PC Julie Nesbitt told BBC Radio 4's Today programme the police service is "the people without whom the rest of the public services shouldn't function and therefore we should be treated according to that".

'Too fast'

Shadow home secretary Yvette Cooper, who marched with police officers at a separate protest, said 16,000 were being lost across the country which was "irresponsible and taking a risk with crime".

If there is a surprise at the action today, it is that we haven't seen more of it

Home Secretary Theresa May told the Commons police officers will still be "well remunerated" and receive "very good" pensions after government reforms are brought in.

"I see an exciting future for policing as a result of the reforms that this government is putting through and that is the message I hope everybody will be taking out to police officers on the streets," she said.

The unions taking part on Thursday are: the Public and Commercial Services Union (PCS), the largest civil service trade union; Unite, representing NHS workers, Ministry of Defence firefighters and others; the University and College Union; the Immigration Services Union; Rail, Maritime and Transport (RMT) union members in the Royal Fleet Auxiliary, and the Northern Ireland Public Services Alliance.