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.
More top news
The guitarist is reportedly in full-time care in Sydney and will not be joining the band for their forthcoming album.
Author Irvine Welsh issued an expletive-laden attack after George Osborne referenced one of his characters in his party conference speech.
Cheryl Cole has been named as the "most dangerous celebrity" online measured by the amount of malicious websites linked to a star's name.