Two men have been released by anti-terror police who have been searching a number of sites in the South East.
Raids were conducted at an Islamic school in Sussex and a string of other addresses in London.
Twelve people remain in custody. Police have warrants of further detention for three people until Wednesday and nine until Friday.
Most of the arrests were made at a south London Chinese restaurant.
Scotland Yard said the arrests were not connected to the alleged transatlantic jet bomb plot or the 7 July attacks.
The remaining men are thought to be held at London's high-security Paddington Green police station.
Sussex Police said searches at the Jameah Islameah Islamic school in Mark Cross, near Crowborough, could take weeks but said no arrests had been made there.
A lake within the grounds of the school will also be trawled.