People arriving at British airports were on Thursday warned to expect delays as hundreds of thousands of public sector workers went on strike against proposed pensions reforms and plans to raise their retirement age.

Many schools across the country were closed and work at airports, courts, government offices, museums and libraries was disrupted after an estimated 600,000 workers walked out of their jobs in the first of a wave of strikes expected in coming months unless the government backs down.

The reforms are part of a series of austerity measures launched by the Conservative-Lib Dem ruling coalition to tackle the economic crisis caused by a huge budget deficit. Workers say the proposals mean they would have to work longer for reduced pension.

Mark Serwotka, general secretary of the Public and Commercial Services Union, said members were left with no choice but to take action as the government was not prepared to “compromise on any of the central issues of the strike”.

“While they are talking, they are not negotiating,” he told the BBC as major trade unions warned of a summer of discontent.

Thousands of protesters, carrying banners with the message “No cuts” and “Cuts hurt”, took out a march through central London. Protests were also held in other major cities.

Prime Minister David Cameron described the strike as “wrong” while the Lib Dem Deputy Prime Minister Nick Clegg said it was a “shame” that workers had resorted to strike when negotiations were still on. Labour Party leader Ed Miliband, while criticising the strike, accused the government of “reckless behaviour”.

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