Coalition ministers have been summoned to a crisis meeting before one of Britain’s biggest ever strikes next month. Around 1.5 million refuse collectors, social workers, town planners, librarians, care home staff and other local government employees are expected to walk out of work for 24 hours on 10 July.

They are infuriated by a pay offer that will result in workers on a salary of £14,000 and above being given only a 1 per cent increase, while those at lower grades will be paid little more than the minimum wage. The industrial action is likely to be supported by up to 500,000 teachers and civil servants.

Union leaders warned this weekend that, following the 2011 public sector walk-out over pension reforms, the coalition will have presided over Britain’s two biggest post-war strikes. Ministers whose briefs cover the public sectors that will be affected by industrial action, such as those in the Department of Local Government and Communities, will meet within the next two weeks to discuss how to keep Britain running through the strike.

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Unite and Unison are currently balloting their members, who are expected to vote for the strike having already rejected the pay offer. The third main union involved, the GMB, last week notified the Local Government Association (LGA) that it is about to hold a similar ballot.

The LGA represents the 6,000 employers, mainly local councils, involved in the dispute. Unions demanded that the LGA pay all workers an extra £1 an hour. Unison now wants £1.20, as there has been a 20p increase in the living wage since the claims were submitted.

It argues that typical local government workers have seen their real pay reduced by 20 per cent since the coalition came to power, as increases have fallen far behind inflation. Union sources also said that negotiations were “very hard” as the LGA had “failed to engage properly”.

Unison general secretary Dave Prentis said last night, “I know how angry our members are at feeling the worth of their pay plummet over recent years. Many have to rely on benefits, food banks or resort to payday loans to make ends meet. This cannot go on. Pay freezes and squeezes are not sustainable as this Government will soon find out.” As rises have been restricted in recent years, so the minimum wage has started to catch up with that of the lowest-paid council workers.

Those on the lowest salary of £12,435 currently receive around £6.45 an hour. The LGA wants to increase this to £6.75, only 25p more than the minimum wage will be when the next rise takes effect in October.

Unite assistant general secretary Gail Cartmail (inset below) said it was “time to take a stand” and that “anger is mounting” among public service workers. She added: “While the Tory-led government has been giving tax breaks to millionaires, local council and NHS workers have been pushed to breaking point. Poverty pay and four years of pay freezes has resulted in many seeing their take-home pay cut by almost 20 per cent in real terms.”

Brian Strutton, GMB national secretary for public services, warned that “schools will shut, bins won’t be emptied, meals on wheels not delivered – this is one of the two biggest post-war strikes”.

Recent local election results meant that Labour become the biggest group on the LGA for the first time in a decade. However, LGA sources said the change will have no impact on its tough stance over pay.

A spokesman for the LGA said: “The employers made their full and final pay offer at the earliest opportunity in order to ensure that our employees would receive their pay increase as quickly as possible in the new financial year.

“We’ve always been available to talk to the unions but the integrity of the negotiating process depends on us being honest when there’s no more room for manoeuvre. Strike action will not change the pay offer but will instead delay by some months extra money getting into employees’ pockets.”