Three men have been arrested in dawn raids over alleged terrorist fund-raising.
The suspects, aged 31, 32 and 43, were detained at separate addresses in Slough, Berks, and taken to a London police station, Scotland Yard said.
The raids were carried out days after a British Airways worker, 30, was arrested at the firm's Newcastle office on suspicion of the same offence.
The office and a residential address were searched on 25 February.
Detectives have been given more time to interview the BA worker, also being held in London.