A Muslim activist who heckled John Reid, the Home Secretary, at a meeting was one of six men arrested yesterday in a series of anti-terrorism raids.

Abu Izzadeen, who was known as Trevor Brookes before he converted to Islam, was detained at his home in Leytonstone, East London.

Four other men were arrested in London. A sixth man was picked up by police in Luton.

The arrests came as the Prime Minister, Mr Reid and other Cabinet members were briefed by the new head of MI5 on the terrorist threat.

Jonathan Evans was speaking at the first meeting of the Government’s committee on security and terrorism, which brings together members of the intelligence agencies, police and Whitehall departments. The committee is supported by a new Office for Security and Counter-terrorism, which will meet weekly under Mr Reid’s chairmanship.

Also yesterday, the senior policeman in charge of counter-terrorism said that al-Qae-da’s leadership in Pakistan was training British citizens to become to become terrorists and directing a series of attempted terror attacks on Britain.

In a lecture to the Policy Exchange think-tank in London, Peter Clarke, the Deputy Assistant Commissioner, said that the threat from the global terror network was “increasing in scale and intensity”.

The six men arrested were taken to Paddington Green police station and questioned about allegations of inciting terrorism overseas and raising money to fund terrorist groups.

Scotland Yard sources said that no armed officers were involved in the arrests and there was no suggestion of imminent attacks in Britain. 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.”

A speech to Muslim community leaders by Mr Reid in Walthamstow, East London, last year was disrupted when Mr Izzadeen began shouting from the floor and resisted attempts to remove him from the building.

His arrest is not connected with that incident nor to a television interview in which he described the July 7 London suicide bombers as “completely praiseworthy”.

The six men, aged between 21 and 35, are being questioned about an event at the London Central Mosque in November 2004, when speeches were made and money was collected.

Anjem Choudary, a friend of Mr Izzadeen, said: “There were six arrests. They are saying it’s in relation to something around November 2004, allegedly collecting funds for terrorism, inciting terrorism. People collect a lot of money for orphans and widows at Ramadan.

“Abu Izzadeen and other individuals are completely innocent. They do not support any terrorist activities in this country or abroad.”

Mr Choudary and Mr Izzadeen are followers of Omar Bakri Mohammed, the extremist cleric who left Britain in 2005 to live in Lebanon and is barred from reentering the country. They were prominent members of the al-Muhajiroun movement, which openly praised Osama bin Laden and the September 11 atrocities, and the Saved Sect organisation, which replaced it.

Mr Izzadeen was arrested in February this year and charged with an offence of encouraging terror under the Terrorism Act 2006. He was released on bail after appearing at City of Westminster Magistrates Court.

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