LONDON – A quarter million mostly peaceful demonstrators marched through central London on Saturday against the toughest cuts to public spending since World War II, with some small breakaway groups smashing windows at banks and shops and spray painting logos on the walls.

Another group of black-clad protesters hurled paint bombs and ammonia-filled light bulbs at police.

Organizers of the March for the Alternative said people from across the country were peacefully joining in the demonstration, the biggest protest in London since a series of rallies against the Iraq war in 2003.

Commander Bob Broadhurst of the Metropolitan Police confirmed that more than 250,000 people had marched peacefully, but said around 500 had caused trouble in London’s main shopping streets.

He said nine people had been arrested, for public disorder and criminal damage. Police said 28 people had been injured during the demonstration, and seven were admitted to hospitals for a range of problems, including shortness of breath and a suspected hip fracture. Five police officers were also injured and one of those had to be treated in hospital for a groin injury.

Police said one group of a few hundred people broke away from the main march, scuffling with police officers and attempting to smash shop windows on two of London’s main shopping streets. Others threw objects at the posh Ritz Hotel in nearby Piccadilly. Members of protest group UK Uncut later walked into the nearby luxury department store Fortnum and Mason and remained inside for a few hours. Police clashed with other demonstrators outside.

But the protests otherwise had a carnival feel. School teachers, nurses and students all marched through central London and rallied in Hyde Park, one of London’s biggest public gardens, with banners, balloons and whistles.

Britain is facing $130 billion of public spending cuts from Prime Minister David Cameron’s coalition government as it struggles to get the country’s large budget deficit under control. The government has already raised the sales tax, but Britons are bracing for big cuts to public spending.

After the country spent billions bailing out indebted banks, and suffered a squeeze on tax revenue and an increase in welfare bills, Treasury chief George Osborne has staked the coalition government’s future on tough economic remedies.

As many as half a million public-sector jobs will be lost, about $28.5 billion axed from welfare payments and the pension age raised to 66 by 2020, earlier than previously planned.

The TUC, the main umbrella body for British unions, says it believes the cuts will threaten the country’s economic recovery, and has urged the government to create new taxes for banks and to close loopholes that allow some companies to pay less tax — an argument that resonates with many of the protesters.

“They shouldn’t be taking money from public services. What have we done to deserve this?” said Alison Foster, a 53-year-old school teacher. “Yes, they are making vicious cuts. That’s why I’m marching, to let them know this is wrong.”

Ed Miliband, leader of the opposition Labour Party, likened the march to the suffragette movement in Britain and the civil rights movement in America. “Our causes may be different but we come together to realize our voice,” he told protesters at the rally.