Radical Muslim Abu Izzadeen was one of six men arrested in police anti-terror raids today.
Scotland Yard said six men were arrested in connection with inciting others to commit acts of terrorism overseas and terrorist fundraising.
They were held this morning by officers from the Metropolitan Police Counter Terrorism Command and local police at five addresses in London and one in Luton. The men were being held at an unnamed central London police station.
Scotland Yard said a number of searches were ongoing in connection with the investigation.
A spokesman said: "The arrests form part of a long-term pro-active and complex investigation into alleged incitement and radicalisation for the purposes of terrorism, as well as alleged provision of financial support for international terrorism."
The six men, aged between 21 and 35, were held at addresses in east London, Southall and Luton at around 5am today.
Izzadeen, a former electrician who lives in east London with his wife and three children, is perhaps best known for his barracking of Home Secretary John Reid last September.
At a speech to British Muslims in Leyton, east London, Mr Reid was interrupted by Izzadeen, who called him "an enemy of Islam" and "a tyrant", accused the British Government of state terrorism and said Prime Minister Tony Blair and US President George Bush could "go to hell".
He was also reportedly involved in protests against the Danish anti-Muslim cartoons and has been linked to radical Islamic group al-Ghurabaa, an offshoot of al-Muhajiroun, both of which are now banned in the UK.
