Around 150 members of the English Defence League have attempted to march from Kings Cross to Whitechapel, East London, causing a major police operation.
The EDL had planned to protest near one of the country's most prominent mosques. However, police kettled the protestors at Aldgate, before moving them towards Tower Bridge.
Around 400 anti-EDL protestors also took to the street, however, the police operation has so far kept the two groups apart.
The EDL decided to flout a ban on marching by the home secretary Theresa May, and conducted what is being described as a "static march".
Earlier today, it emerged that police forces from around the UK will be on the streets of the capital. Around 25 officers from Grampian police - who have remained in London since last month's riots - were seen patrolling in the area.
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Police sources told the Huffington Post UK they were would have a significant presence "throughout the borough of Tower Hamlets" all day.
"Hopefully the EDL will just gather for an hour or so and then disperse," the a source said. "But we're having to prepare for any eventuality."
According to comments on Twitter, police officers have been stopping and searching possible EDL members at Kings Cross Station.
On Saturday afternoon approximately 200 EDL supporters, surrounded by police, gathered outside the Flying Scotsman pub in Kings Cross singing England football songs.
A counter-demonstration by anti-racist groups is taking place in Whitechapel, organised by the group Unite Against Facism and supported by both the East London Mosque and Central Synagogue.
Dilowar Khan, director of the East London Mosque and London Muslim Centre, said: “The EDL has been inciting hatred against Muslims for a couple of years now. We request that residents to come out and show people the solidarity that we have here in Tower Hamlets.”
Leon Silver from East London Central Synagogue said: “Facists like to make out that we are all enemies and don’t get on. This lie is as disgusting as it is untrue. We live in harmony and peaceful coexistence with our neighbours. The EDL are nothing but fascists and racists trying to come into the area where we live.”
A statement on the EDL's website said the police had told them they would not be allowed to raise their flags or banners, and that anyone doing so would be removed from the area. A ruling the EDL branded "absolutely ridiculous".
"We are certainly not happy about this clear violation of our right to peaceful protest, but we would rather everyone reached the demonstration site than saw people ejected early on," the statement said.
Metropolitan Police Chief Superintendent Julia Pendry said: "Following the appalling disorder in London in recent weeks, it's important London, its communities and businesses, can return to normality."