Up to 750,000 public sector workers went on strike across the United Kingdom on Thursday, closing or disrupting schools, colleges, courts, airports and ports.

The 24-hour walkout by four unions representing teachers and other public-sector workers was in protest of plans to make them retire later, pay more toward their pensions, cut jobs and freeze pay.

The stoppage was one of the biggest protests against the government's 111-billion-pound ($178.29 billion) austerity drive since the coalition was formed last year.

"We face a defining battle for our movement. Real leadership is required, based on a strategy of no cuts, no concessions to pension robbery," said John Mclnally, vice-president of the Public and Commercial Services Union, the fifth-largest trade union in the UK with around 290,000 members.

According to the Department for Education, at least one-third of schools in England were closed, a further one-third faced disruption and the remainder were open as usual.

The University and College Union said the strikes would cause disruption at 75 universities and 350 further education colleges.

Camden, in north London, where only four of the borough's 58 schools were fully open, was one of the worst-hit areas.

Lu Xiang, a Chinese IT manager who works in Camden, told China Daily that he had to look after his 9-year-old daughter at home because her school was closed.

"I'm happy that I won't go to school today, I can do anything I like," said his daughter Lu Yuxin.

Police leave was cancelled in London, where union leaders and thousands of activists took part in a march, followed by a rally in Westminster.

Travelers were warned to expect delays on arrival to the UK as immigration and customs officers joined the strike.

A statement on Heathrow Airport's website said: "Due to strike action by UK Border Agency staff at all UK airports, passengers arriving at Heathrow are likely to experience a longer wait time at passport control."

Passengers were advised to consider traveling on a different day to avoid disruption as hundreds of staff walked out.

British Prime Minister David Cameron launched a fresh attack on the strike, while business leaders warned it would have a "significant impact" on industry.

Cameron has repeatedly said the strikers represent a minority of the 6.2 million people who work in the public sector, according to Dow Jones report.

Speaking in the House of Commons, he said he hoped "as many mums and dads as possible" would be able to take their children to school despite the action.

Based on the fact that people are living longer and in order to ease the burden on private-sector taxpayers, the British government wants public-sector workers to retire later and contribute more toward their pensions.

However, unions whose members were angry at a pay freeze and some 300,000 planned job cuts said the proposals were unfair and the government had ruled out compromise on any of the key issues.