Tens of thousands are expected to march through London on Saturday in what is likely to be the largest demonstration in Britain this year against government austerity measures.
Prime Minister David Cameron's push to reduce one of Europe's biggest deficits has drawn howls of protest, with critics arguing that austerity is not working and calling for urgent measures to stimulate growth.
The Trades Union Congress (TUC), Britain's umbrella union body, said people from across the country would join Saturday's "A Future That Works" march through central London, and there will be similar demonstrations in Glasgow and Belfast.
"The evidence is mounting that austerity is failing," said TUC General Secretary Brendan Barber.
"More than 2.5 million people are out of work, a further three million are not working enough hours to make ends meet and wages have been falling every month for the last three years."
In March last year at least 250,000 people joined a TUC-organised protest in London, the largest since a mass rally against war in Iraq in 2003. It turned violent after radical splinter groups broke away from the main march.
Police made some 200 arrests that day as masked youths fought running battles with riot police and attacked banks and luxury stores in the West End shopping and theatre district.
"We don't want to see a repeat of that," said a spokesman for the TUC, which has booked 250 buses to bring people to London from all over Britain. "We don't want anything to detract from the message which we're hoping to get across."
Anarchist and radical groups have indicated on websites that they are planning to attend on Saturday, although there is no overt discussion of plans for violence.
"We do have a policing plan in place but it will be based on intelligence up to the day," a London police spokesman said. "We've worked very closely with the TUC over the plans so we're hoping for a very peaceful day."
Earlier this month Cameron warned that Britons faced more "painful decisions" as his coalition government dealt with an economy that has slipped back into recession, and said he would not waver from austerity measures.
Most economists expect the government to announce lower growth forecasts in December, which could play havoc with Cameron's deficit reduction plans and potentially force him to stretch out spending cuts well beyond the 2015 election.
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