The majority of those arrested are thought to have been supporters of United Against Fascism, and the BNP group cheered as handcuffed demonstrators were led onto a red double decker bus which had “Special Service” as its destination.

The fighting came despite calls for peace from police and the family of soldier Lee Rigby, who was hacked to death in Woolwich last month in what police are treating as a terrorist attack.

One BNP supporter who suffered a large cut to his nose said: “I’ve put my best suit on today and come out for a peaceful demonstration and this is what’s happened. And to think they call us thugs!”

BNP activists holding banners saying “hate preachers out” were heavily outnumbered by anti-fascists with “smash the BNP” and “say no to Islamaphobia” signage.

The group of counter-protesters chanted “fascist scum” and “you racist Nazis” at their rivals.

Nick Griffin, whose party was banned by police from protesting in Woolwich over fears of “serious disruption to the life of the community” and the potential for “serious disorder”, arrived at around 2.30pm to the sound of the national anthem.

The BNP leader said the tragic murder of Lee Rigby would not be an “isolated” incident, adding: “We’re pointing out that it will happen again and again and again until the West disengages with Islam and they leave our country.”

Dozens of police attended the demonstration, accompanied by sniffer dogs deployed to calm the situation as tempers flared.

Scotland Yard said that the anti-fascists had gathered in a pre-arranged penned area – but some were unwilling to remain within that area.                                               

A spokesman said: “Due to police concerns about serious disruption to the life of the community, and the potential for serious disorder should this counter protest confront the BNP organised protest, police have imposed conditions under Section 14 of the Public Order Act.

“Those conditions state that the protest must take place in Whitehall Gardens junction with Whitehall.

“A group of about 300, also believed to be part of the UAF protest, were stopped in Old Palace Yard junction with Abdingdon Street.

“This group have now been notified of the conditions imposed under Section 14 and requested to move to Whitehall Gardens to continue their protest. Officers are in negotiation with this group.”

Those held by police were arrested for breach of the Section 14 order.