Tens of thousands of demonstrators descended on the British capital Saturday in a noisy but peaceful protest at a government austerity drive aimed at slashing the nation's debt.

Union members, anti-war campaigners, left-wing leaders, community groups and other activists marched through London's streets.

They have been speaking out against reductions to public sector spending cuts and wage freezes aimed at reining in a debt that stands at more than £1 trillion ($1.68 trillion Cdn).

Although the austerity program has had some modest successes — the country's deficit has dropped slightly — the U.K. economy has shrunk for three consecutive quarters amid cuts at home and economic turmoil on the continent.

Police officers scuffle with demonstrators during a protest march organized by the Trades Union Congress on Oxford Street in central London. (Suzanne Plunkett/Reuters)

Brendan Barber, whose Trades Union Congress helped organize the march, said the message of Saturday's protest was that "austerity is simply failing."

"The government is making life desperately hard for millions of people because of pay cuts for workers, while the rich are given tax cuts," he said.

Britain borrowed £13 billion in September alone, and with other European countries — including next door neighbour Ireland — struggling to make good on their debt, and there is a general consensus that the U.K. budget needs to be rebalanced.

But the right-leaning government did little to endear itself with ordinary Britons when it reduced income taxes for the country's wealthiest citizens earlier this year. And its leadership has struggled to fight perceptions of elitism which rankle many in this class-conscious country.

On Friday, the Conservative Party's chief whip stepped down following a dispute over whether he'd described officers guarding the prime minister's official residence at Downing Street as "plebs" or warned them to "learn your (expletive) place."

News of Andrew Mitchell's resignation broke just as word was getting around that Treasury Chief George Osborne had been spotted by a journalist sitting in a first class train carriage with a second class ticket.

Osborne paid for an upgrade, but the story's humour was irresistible. Newspapers lavished coverage on what many nicknamed "The Great Train Snobbery," and Osborne's misadventure was a popular talking point at the rally, which marched through the city beneath huge red and purple balloons emblazoned with union logos.

Even opposition Labour Party leader Ed Miliband, known for his close ties with unions, was booed when he told protesters gathered in London's Hyde Park that some cuts would have to be made one way or the other.

"It's right that we level with people," he argued. The cheers returned after he criticized what he described as "self-defeating austerity."

Unlike some rallies elsewhere in Europe, Saturday's march appeared to go off without violence, although following the rally a splinter group of protesters — some wearing the Guy Fawkes masks associated with the Anonymous movement — ran through the streets of London with police in tow.

A force spokesman said there had been no arrests.

One group of children dressed up as government workers, including a nurse and a traffic warden. Another child, dressed as a chef, held up a sign warning that Prime Minister David Cameron was "a recipe for disaster."

Official crowd estimates were not immediately available, although journalists at the scene said the protesters were tens of thousands strong. Organizers said that more than 250 buses were booked to bring people to London.

Similar protests were also held in Belfast, Northern Ireland's capital, and Glasgow, Scotland's biggest city.