The leader of Britain's far-right, anti-Islamic English Defence League (EDL) has quit, saying he felt he could no longer keep "extremist elements" in the group at bay.
In a surprise move on Tuesday, EDL leader Tommy Robinson announced his resignation - along with that of his deputy Kevin Carroll - through Quilliam, a think-tank that works to counter Islamic extremism.
"Quilliam is proud to announce that Tommy Robinson and Kevin Carroll, the leaders of the anti-Islamist group, the English Defence League (EDL), have decided to leave the group," it said in a statement.
Mr Robinson appeared to confirm his resignation, posting a link to the statement on his Twitter page and adding: "Hope people listen to my reasons."
Mr Robinson and Mr Carroll set up the EDL in 2009 and the group has since become well-known for organising street protests against what it says is the spread of radical Islam in Britain, but it has been accused of being Islamophobic and attracting racists.
Its protests have sometimes sparked clashes with anti-fascist protesters.
Mr Robinson said in the statement issued by Quilliam: "I have been considering this move for a long time because I recognise that, though street demonstrations have brought us to this point, they are no longer productive."
"I acknowledge the dangers of far-right extremism and the ongoing need to counter Islamist ideology not with violence but with better, democratic ideas."
Quilliam said it had been working with Mr Robinson to achieve his "transition", which it said represented "a huge success for community relations in the United Kingdom".
"We hope to help Tommy invest his energy and commitment in countering extremism of all kinds, supporting the efforts to bring along his former followers and encouraging his critique of Islamism as well as his concern with far-right extremism," the think-tank said.
"We call all of Tommy's former colleagues in the EDL to follow in his footsteps and also call on Islamist extremist leaders to follow this example and leave their respective groups."
Quilliam was founded by Maajid Naawaz, a former Islamic extremist, in a bid to discourage British Muslims from turning to fundamentalism.
Islam is Britain's second biggest religion, with the number of British Muslims rising from 3 per cent to 4.8 per cent over the last decade, according to census figures released in 2012.