English Defence League leader Stephen Lennon has been arrested over an alleged assault in Luton on Saturday morning.
It is believed the victim was Saiful Islam, known for preaching his extremist views in Bury Park.
The pair featured in Channel 4 documentary Proud and Prejudiced earlier this year, and a You Tube video of an altercation between the pair in Bury Park last year has been viewed nearly 300,000 times.
A spokesman for Beds Police said a man was assaulted in New Bedford Road at about 10.15am by five men who got out of a black BMW.
He was punched and kicked and lost his mobile phone and keys in the incident, and his injuries are described as “reddening of the left eye”.
Police confirmed a 29-year-old man was being held on suspicion of assault.
Lennon, who calls himself Tommy Robinson, is currently being held by police on suspicion of conspiring to cause a public nuisance after police intercepted a group of 53 EDL members on their way to east London on Saturday.
The English Defence League has released a statement saying everyone arrested on Saturday, apart from Lennon, was bailed yesterday and that he was also being held on suspicion of entering the US illegally following a trip to New York in September.
Also among those understood to have been arrested on Saturday was Kevin Carroll, who is standing in the police and crime commissioner elections for Bedfordshire.