On platform one at Bolton train station in England a mob of about 100 men punch the air in unison as a chant goes up: "Muslim bombers, off our streets! Muslim bombers off our streets!"

Their voices echo loudly, and as more men suddenly appear, startled passengers move aside. The protesters wave St George's Cross flags - the red and white English national emblem - and raise placards.

Some wear balaclavas, others black-hooded tops and there is an air of menace to these men.

These are some of the most violent soccer hooligans in Britain and today they have joined in an unprecedented show of strength.

Standing shoulder to shoulder are notorious gangs such as Cardiff City's Soul Crew, Bolton Wanderers' Cuckoo Boys and Luton Town's Men In Gear: a remarkable gathering given that on a match day these men would be fighting each other.

Today they are not here for football; it is politics that has drawn them. Their destination is Manchester to support a protest by the newly formed English Defence League.

The police are here in force, too. "Take that mask off," barks a sergeant to one young man. The man does so immediately but retorts: "Why are they allowed to wear burqas in public but we're not allowed to cover our faces?"

The sergeant snaps back: "Just do what you're told."

Says a man with a West Country accent standing next to me: "It's always the f*****' same these days. One rule for them and another for us. I'm sick of this country."

He draws on a cigarette before flicking it to the ground in disgust. He starts to complain again, but when the public address system announces the arrival of the train to Manchester Piccadilly, he raises his hands above his head and starts another football favourite: "Rule Britannia, Britannia rules the waves ... "

His companions join in singing, and as the train comes to a halt beside the platform the crowd surges forward. The carriages are almost full, so the men pack into aisles followed by police speaking into radios.

A group of young men drinking beer at a table eye the protesters warily, but one protester wearing a baseball cap notices their fear and reassures them.

"It's all right lads, nothing to worry about. We're protesting against radical Islam. Come and join us," he says, and as the train draws nearer to Manchester, the singing starts again. "Eng-e-land, Eng-e-land, Eng-e-land ... " the men sing rowdily.

The English Defence League is in town.

The league seemed to spring from nowhere last year, but since its formation the far right movement has held more than 20 large protests in Britain's cities.

Although it claims to be a peaceful group, violence has erupted at most league demonstrations, with its supporters fighting on the streets against Muslim youths and a group called Unite Against Fascism, an umbrella organisation consisting of mainly students and trade unionists and formed in 2003 to oppose the far right.

Nearly 200 people have been arrested, weapons have been seized and city centres have been brought to a standstill.

Britain has not witnessed such street violence for many years, and although both sides blame each other for the trouble, there are fears that the league - despite its official multiracial stance - has become a ready-made army for neo-Nazis and other extremists who for years have operated underground.

All mainstream political parties in Britain have criticised the league. Communities Secretary John Denham MP compared the group to Oswald Mosley's Union of British Fascists, which ran amok in the 1930s.

Now, with tinderbox northern towns such as Bradford and Oldham - both of which witnessed race riots in 2001 - among the league's stated targets for this year, a countrywide police team set up to combat domestic extremism, the National Extremism Tactical Co-ordination Unit, has been investigating the movement.

I had met members of the league for the first time in a derelict building in Luton, near London, three weeks before the Manchester rally.

They had agreed to talk on the condition that I did not identify them. Eleven men turned up.

All wore balaclavas and most had black league hoodies with "Luton Division" on the back. A man using the pseudonym Tommy Robinson did most of the talking and explained the movement's background.

"For more than a decade now, there's been tension in Luton between Muslim youths and whites. We all get on fine - black, white, Indian, Chinese - everyone does, in fact, apart from some Muslim youths who've become extremely radicalised since the first Gulf War.

"Preachers of hate such as Anjem Choudary have been recruiting for radical Islamist groups in Luton for years. Our Government does nothing, so we decided we'd start protesting against radical Islam, and it grew from there," he said.

With Islam being Europe's fastest-growing religion - Muslim populations are projected to expand rapidly in coming decades - the group's fear that traditional British culture is under threat have been exacerbated.

Robinson could barely conceal his anger as he described radical Muslims protesting as the Royal Anglican regiment paraded through the town on its return from Afghanistan last May.

Following the incident, he and others set up a group called United People of Luton. After linking up with a Birmingham-based group called British Citizens Against Muslim Extremists and a group calling itself Casuals United, they realised there was potential for a national movement.

Robinson said members wore balaclavas to protect their identities because league members had been targeted by Muslim extremists.

But although the league publicly espouses peaceful protest, there is growing concern over its secrecy and quasi-paramilitary appearance - as well as some of its membership.

According to the international anti-fascist magazine Searchlight, far-right British National Party activists and other fascist extremists are at the core of the league.

The respected publication's allegations have been backed by a former league member called Paul Ray who claimed that the group had been hijacked by the anti-immigration British National Party.

Then there is Casuals United.

The group came to the fore about the time the English Defence League was formed. An unprecedented alliance of football hooligans, it was the brainchild of Jeff Marsh, a member of Cardiff City's Soul Crew who has been convicted four times for violent offences.

This included a two-year jail sentence for stabbing Manchester United fans. Marsh has now taken a back seat, so the public face of Casuals United is fellow Welshman and Soul Crew member Mickey Smith.

Casuals United makes full use of modern communications and uses social networking websites such as Facebook to organise the 50 or so gangs that are recruiting members around Britain.

The league and Casuals United claim to be separate, but the link becomes clear after I meet Joel Titus. Titus, 18, an Arsenal fan with a club tattoo on his right calf who runs the league's youth division.

He refuses to speak about the group's relationship with Casuals United but a text I later receive from him before a protest in London reads: "Right lads, the 'unofficial' meet for the 31st (London) is going to be 12 o'clock at The Hole In the Wall pub just outside Waterloo station. I will be there just before that. Remember lads, were [sic] going as Casuals United and if you could obtain a poppy to wear, it would make us look good, even if we are kicking off. lol. Cheers lads. Joel 'Arsenal' Titus."

In London that day, fighting erupted though not between the league and its original targets, radical preacher Anjem Choudary and his extremist followers in the now-outlawed Islamist group Islam4UK - their planned march was cancelled over fears of violence.

The league's ruckus was with neo-Nazi group Combat 18.

An account on neo-Nazi website Stormfront said 400 nationalists turned up in London to demonstrate against Islam4UK's march to Downing Street and that fighting began afterwards when members of the English Defence League started singing anti-German songs in a pub.

"We ended up kicking off with about 50 to 60 EDL, who were throwing fire extinguishers, pint glasses, bottles, and various other things," a neo-Nazi posted.

Other neo-Nazi groups, including the British People's Party and the British Freedom Fighters, have also participated in league protests, despite their opposition to the league's multiracial position.

The league's credentials as a peaceful protest group are further undermined by postings by its own supporters on Facebook. Ahead of a rally in Leeds, comments were made about Muslims, including one by a supporter called Aiden Hirst: "Kill every single 1 of the f******."

Threats are not just aimed at Muslims.

Photographs and addresses of critics are also passed between league members online, and journalists have been sent death threats in the form of "EDL fatwas".

The high command of the league is much more astute than Titus or Smith and distances itself from violence.

In a Covent Garden pub I meet a computer expert from London called Alan Lake who runs a website called Four Freedoms. Last summer he contacted the league and offered to fund and advise the movement.

His aim, he says, is to unite the "thinkers" and those prepared to take to the streets.

He describes this marriage as "the perfect storm coming together", adding that street violence is not desirable but perhaps inevitable. "There are issues when you are dealing with football thugs - but what can we do?" He strongly criticises fascist organisations, however, and says that one of his conditions for backing the movement is that it does not associate with far-right groups.

"There are different groups infiltrating and trying to cause rifts by one means or another, or trying to waylay the organisation to different agendas. The intention is to exclude those groups and individuals."

The English city of Stoke witnessed the largest English Defence League protest so far when in January about 1500 supporters turned out.

Violence erupted again and 17 people were arrested and four policemen injured.

Football hooligans from Aston Villa and Wolverhampton Wanderers fought each other, despite being fellow league supporters.

A video on YouTube showed vehicles being attacked and a police officer being kicked by a mob after he fell to the ground.

This weekend, the EDL will protest in the northern town of Bolton and the fear of many is that the perfect storm is coming together for the far right.

At the league protest I attended in Manchester, 48 people were arrested during street violence, including supporters of Unite Against Fascism, which has also attracted a minority intent on violence.

In the aftermath, the Bolton Interfaith Council, echoing the concerns of many, issued a stark warning that race relations were under threat in Britain.