LONDON -- The Metropolitan Police counter-terrorism command arrested nine men on suspicion of being members of banned organizations as well as supporting and encouraging terrorism.

The men, ranging in age from 22 to 51, were in custody Thursday in central London police stations.

Scotland Yard also raided homes, businesses and community centers as part of the probe. Searches were underway Thursday at 18 sites in London and one residence in Stoke on Trent.

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Police said in a statement that the arrests and searches were part of an ongoing investigation into Islamic extremist-related terrorism rather than any immediate risk to public safety.

One of the men detained was radical preacher Anjem Choudary, organizer of banned UK Islamic fundamentalist group "Islam4UK." Choudary is well-known to British law enforcement, and has for years organized demonstrations against Western military action in Middle East and in favor of bringing Islamic Sharia law to Britain.

He has publicly expressed support for the Sept. 11 attacks on the U.S. and the July 7 bombings against London's transport network.

Choudary, who was also linked to the men behind the brutal daylight murder of British solider Lee Rigby in south London, has been questioned by police previously.

The preacher has been a prominent member of several radical Islamic groups in the U.K. He was a top aide to the leader of "al Mujaharoon," another radical preacher named Omar Bakri Muhammad. Muhammad fled to Lebanon -- where he still lives freely, in the years after the Sept. 11, 2001 terror attacks.

The group was officially banned, along with Islam4UK, in 2010.