A gang of 20 protesters were arrested outside the US embassy in London today on suspicion of representing the recently-banned extremist group Muslims Against Crusades.
Activists said demonstrations over the use of American drones in Pakistan had been organised by a group calling itself United Ummah.
But Scotland Yard intervened this afternoon after members were linked to the banned group involved in the burning of poppies on Armistice Day last year.
Muslims Against Crusades (Mac) joined the likes of al-Qa'ida on a list of terrorist organisations banned in the UK after an announcement by Home Secretary Theresa May last month.
The move to proscribe the group led to it cancelling its "Hell for Heroes" demonstration against Remembrance commemorations, which was due to take place outside the Royal Albert Hall, where poppies were burned last year.
A handful of protesters remain at the scene in central London this afternoon.
A Scotland Yard spokesman said that in addition to the 20 arrests surrounding the banned group, two others had been made for obstruction and violent disorder.
"They are all in custody at central London police stations," a spokesman said. "A small number of people remain at the demonstration."
The demonstration began at noon outside the embassy which has seen a string of clashes between protesters in recent years.