Far-right groups are planning their biggest mobilisation for 30 years this weekend with more than 50 demonstrations planned in towns and cities across England.

Anti-racism campaigners have branded Saturday a "day of hate" after identifying 55 English Defence League (EDL) events as well a BNP march in London.

The events are seen as the latest attempt by UK far-right groups to exploit the murder of the British soldier Lee Rigby, who was stabbed to death in Woolwich, south-east London, last week.

"Towns and cities across England are going to have EDL events – many of them for the first time – and this is about the EDL taking their message of hate and division to communities across the country to try to stoke tensions and provoke a response," said Nick Lowles from Hope not Hate.

"It is going to be a very tense weekend and it represents the biggest far-right mobilisation we have seen in this country for 30 years."

The BNP leader, Nick Griffin, had planned to stage a six-mile march from Woolwich to Lewisham in south London on Saturday. But on Thursday afternoon the Metropolitan police imposed restrictions on the march, changing the route to central London between Millbank and the Cenotaph in Whitehall, because of fears that it could result in "serious disorder, serious damage to property, and/or serious disruption to the life of the community".

Commander Simon Letchford said: "The murder of Lee Rigby in Woolwich last week shocked our city. The right to protest is a fundamental part of our society, however, such an evocative mix of views being expressed in communities still hurting from Lee's murder could have resulted in ugly scenes on our streets."

Some of the biggest EDL demonstrations are expected in Birmingham, Luton and Leeds and police forces across England have been holding emergency meetings this week to work out how best to maintain order.

A spokesman for the Association of Chief Police Officers said: "Police are aware of a number of demonstrations planned for this weekend. Forces across the country will be working closely with local communities as always to ensure these pass off with minimum disruption. While we will do all we can to facilitate peaceful protest, those taking part should be clear that the police will uphold the law."

The EDL was a dwindling force before Rigby's murder, struggling to attract more than a few hundred supporters to its events. But since his death the group, which claims it is a peaceful and non-racist organisation, has held three major demonstrations – all of which have been marred by violence and running battles with the police.

"We know from bitter experience the violent and provocative reality of these events," said Lowles.

Anti-racist campaigners are planning "community unity" events in opposition to the EDL and BNP on Saturday. Weyman Bennett from Unite Against Fascism said it was working with faith groups and trade unions to organise wherever the far right gathered. "We want to show that we are united in our opposition to the EDL and BNP and their attempt to use the tragic death of this young man for political ends."