British police clashed with bottle-throwing protesters at a London tourist landmark early Sunday, overshadowing a peaceful march by more than 250,000 people against government spending cuts.
At least 214 people were arrested and 84 people were hurt when a small group of "criminal" demonstrators broke free from Saturday's main rally, the biggest in the capital since protests against the Iraq war in 2003.
A group of several hundred masked rioters attacked the iconic Ritz Hotel, occupied a luxury food store, smashed up shops and banks and started a bonfire in historic Trafalgar Square before police finally contained them.
The original march called by unions on Saturday drew health workers, firefighers, teachers and their families, including children, to oppose the Conservative-Liberal Democrat coalition's austerity measures.
"I think it's a game of two halves. Two hundred and fifty thousand people came to central London and protested peacefully," said Commander Bob Broadhurst of Scotland Yard, who led the police operation.
"But what we have had unfortunately is a group of criminals, nothing to do with that march, have decided to -- on their own steam -- attack buildings in central London and attack police officers," he told Sky News.
Several hundred black-clad protesters covering their faces with scarves hurled fireworks, petrol bombs and paint at police, AFP reporters saw.
Clothes store Topshop and banks HSBC and Lloyds had their windows smashed, while some protesters hurled missiles at the five-star Ritz Hotel.
A group of protesters occupied luxury food store Fortnum and Mason and sprayed graffiti on the building until police sealed off the premises and arrested those coming out.
Police said officers came under "sustained attack" at Trafalgar Square, site of the famous Nelson's Column and of four huge bronze lions. Rioters there were still throwing bottles at police into the early hours of Sunday.
Thirty-one police officers and 53 members of the public were injured in the violence, police said. Sixteen members of the public and 11 police needed hospital treatment.
The 214 arrests were for public order offences, criminal damage, aggravated trespass and violent disorder, said police.
About 4,500 police officers were deployed for the protest after several British student rallies descended into chaos last year, with one culminating in protesters damaging the car carrying heir-to-the-throne Prince Charles and his wife Camilla.
The violent end to Saturday's rally came after organisers the Trades Union Congress (TUC) said between 250,000 and 300,000 people had protested peacefully earlier.
Public sector workers, students and pensioners waving signs which read "Don't Break Britain" and "No to Cuts" thronged the streets of the capital.
Many families with children were among the protesters and the air was filled with the low-pitched bellow of vuvuzela trumpets.
TUC chief Brendan Barber said he "bitterly regretted" the violence.
"I don't think the activities of a few hundred people should take the focus away from the hundreds of thousands of people who have sent a powerful message to the government today," he said.
The march started by the river Thames, passed the Houses of Parliament and Prime Minister David Cameron's Downing Street residence before ending in a rally in Hyde Park addressed by opposition Labour Party leader Ed Miliband.
"Our struggle is to fight to preserve, protect and defend the best of the services we cherish because they represent the best of the country we love," Miliband told the rally.
It was the largest protest in London since one million people marched against the Iraq war in February 2003.
After coming to power in May, the coalition announced cuts worth £81 billion (ê131 billion, 92 billion euros) over five years to slash a record public deficit it blames on the previous Labour government.
The cuts involve most government departments, with the loss of 300,000 public service jobs and pay freezes for civil servants.