A tenth suspect has been arrested in connection with the stabbing death of UK soldier Lee Rigby in Woolwich near London.
The man in his 50s was arrested in a neighborhood in southeast London on suspicion of conspiracy to commit murder.
There were no further details on the suspect's identity.
The arrest came amid protests by the far-right demonstrators in central London.
The group of about 1000 supporters of the English Defence League (EDL) clashed with so-called anti-fascist protestors during the rally.
More from GlobalPost: What makes Woolwich an act of terrorism?
Out of the 10 people arrested over the murder of Lee Rigby, four have been released on bail, two released without charge and four remain in custody.
The two main suspects Michael Adebolajo, 28, and Michael Adebowale, 22 - both British citizens and converts to Islam - remain in hospital in stable condition after being shot by police officers during the incident.
Questions still remain about what British secret services knew about the two men before the murder.
There are allegations that Adebolajo, who was arrested in Kenya in 2010 after attempting to alleged join an Islamic militant group in Somalia, had been actively recruited by MI5.