The trouble came at Euston station, where about 750 people began attacking police and destroying property. At one point rioters overturned an empty police van, to roars of approval from bystanders.
The violence erupted soon after 6.30pm, at the end of a day in which protesters marched through London distributing leaflets condemning the World Trade Organisation.
The well-publicised demonstration began at 9am when a handful of protesters gathered at Euston before starting a disorganised march around the capital's streets. By early evening the crowd had swollen to more than 400, who occupied the concourse of the station. At first campaigners were happy to listen to speeches and dance to drummers, but there was a sense that the day's previously peaceful mood had changed.
At 6.30pm the crowd, estimated by police at almost 800, left its original position and moved out of the station, where it confronted a line of uniformed police. At this point, demonstrators began attacking police, using placards and signs. Riot police carrying shields and helmets and armed with batons were quickly ordered in. A series of running fights with demonstrators ensued as police tried to move them back with a series of charges.
Just how many of the original demonstrators were involved in the violence was hard to ascertain, but there seemed to be a hard core of no more than 75, cheered by hundreds of onlookers. Having confronted the rioters, the police chose to withdraw and surround the demonstrators who had congregated beneath buildings outside the station.
The rioters overturned an empty police van, smashing its windows and attempting to set it on fire using burning placards. Onlookers chanted: "Burn it, burn it", and cheered as one man carrying a flaming placard tried to set fire to the van.
In the run-up to yesterday's demonstration there had been fears of a repeat of the summer's demonstration in the City of London, which turned to violence and caused damage put at millions of pounds. As a result many institutions in and near the City organised special security measures yesterday. News International, publisher of The Times and The Sun, sealed off its Wapping headquarters and hired 420 extra security guards, fearing a possible attack.
The policing of yesterday's demonstrations was the first time a new joint operation involving three police forces was put into action. Set up in the aftermath of June's riots, Operation Benbow was co- ordinated by a 50-strong team of officers based at New Scotland Yard.
Officers from the Metropolitan Police, City of London Police and British Transport Police were able to follow the progress of the demonstrations on video monitors.
As well as the hundreds of uniformed officers on duty at locations considered vulnerable to attack, plain-clothes spotters mingled with the crowds looking for known troublemakers and targets who are wanted for arrest.
At Euston the demonstrators were being secretly filmed and officers in riot equipment were on stand-by in vans in case violence broke out.
Earlier in the day a main suspect from the June riots was identified by an undercover officer and arrested at Liverpool Street station.Reuse content