Terror police began the raid on Abu Qatada's London home at 6.30am on Thursday, Scotland Yard said, before the radical preacher was arrested.
Another residential home and a business were also searched on Thursday, while a search on a third property is ongoing, the spokesman said.
The searches were carried out in connection with ongoing inquiries by the Counter Terrorism Command, he added.
No arrests have been made in connection with the police investigation.
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