Members of Unison in England, Wales and Northern Ireland voted by 55% to 45% to take industrial action after rejecting a 2.45% pay offer.

The union's negotiators will decide on Tuesday what action to recommend to the national strike committee on Friday, but a two day strike in mid-July is expected to be called, followed by further stoppages if the deadlock is not broken.

Social workers, housing benefit staff, teaching assistants, dinner ladies, cooks, cleaners, architects, traffic wardens and refuse collectors will join the strike in the biggest show of industrial unrest for years.

Jobcentre and benefit office workers and other civil servants could take industrial action later in the year in separate rows, while probation officers, Ofsted inspectors, meat and hygiene inspectors and further education staff are also in dispute over pay, highlighting the breadth of anger and simmering unrest across the public sector.

Dave Prentis, Unison's general secretary, said of the council workers' ballot: "This is a solid vote for action and a clear message to the local government employers that our members are willing to fight for a decent pay rise.

"They are fed up and angry that they are expected to accept pay cut after pay cut while bread and butter prices go through the roof. Most of them are low-paid workers, who are hit hardest by food and fuel price hikes, and they see the unfairness of boardroom bonanzas and big City bonuses."

Unison said 250,000 council workers earned less than £6.50 an hour, most of them women, and were not prepared to accept below inflation pay rises. The unions were claiming a 6% pay rise or 50p an hour, whichever was greater.

Employers pointed out that almost 600,000 workers were balloted, but the turnout was 27%, although union officials said opinion had hardened since workers voted, because of rising inflation.

A Communities and Local Government spokesman said: "Central Government does not participate in local government pay negotiations, which are rightly a matter for the local government employers and trade unions. "However, we are disappointed that Unison has decided to take strike action, with the unfortunate disruption that this will bring to some local services."