Trouble has continued to flare late into the night as hundreds of people attempted to hijack the massive anti government cuts demonstration in central London.
Riot police fought activists in Trafalgar Square as violent protesters threatened to overshadow the TUC rally in Hyde Park which had earlier passed off peacefully. A Metropolitan Police spokesman said between 200 and 300 people had gathered at the landmark location late on Saturday evening.
He said: "A large number from the crowd are throwing missiles and have attempted to damage the Olympic clock within the square. Officers have come under sustained attack as they deal with the disorder and attempted criminal damage."
In stark contrast, the daytime demonstration was hailed a "fantastic success" by trade unions as people from across the UK marched through central London.
Organisers estimated between 400,000 and 500,000 teachers, nurses, firefighters, council and NHS workers, other public sector employees, students, pensioners and campaign groups converged on the capital.
But during the good-natured protest hundreds of activists not connected with the union rally clashed with police in the West End. Officers were attacked as they tried to stop demonstrators smashing their way into banks and shops.
Commander Bob Broadhurst, who led the police operation, said: "I wouldn't call them protesters. They are engaging in criminal activities for their own ends."
Labour leader Ed Miliband condemned the violence which erupted away from the march, saying: "Hundreds of thousands of people peacefully protested today. They are the true voice of today's march I unequivocally condemn those who have committed acts of violence. There is no excuse for it. It is unlawful and wrong."
Paint, fireworks and flares were thrown at buildings, while the outnumbered police were attacked with large pieces of wood. Branches of HSBC, RBS, Santander and Topshop were among those to have their windows smashed.
A total of 214 arrests were made during the day for a variety of offences including: public order offences, criminal damage, aggravated trespass and violent disorder, with people in custody at various London police stations, the Metropolitan Police later said.