Three men were arrested in a series of dawn raids for alleged terrorist fund raising, police have said.
Anti-terrorism officers swooped on separate addresses in Berkshire just days after a British Airways worker was arrested on suspicion of the same offence.
The men were being questioned at a central London police station.
A Scotland Yard spokesman said: "At 5am on March 3 three men were arrested in Slough for an alleged offence of terrorist fund raising.
"The men aged 31, 32 and 43 were arrested at separate residential premises by officers from the South East Counter Terrorism Unit as part of a joint operation with the MPS Counter Terrorism Command.
"The men have been taken to a central London police station where they will be interviewed by police.
"Searches are being carried out in connection with the arrests."
A 30-year-old British Airways worker was held at one of the air company's offices in Newcastle last Thursday over terrorist fund raising.
Officers swooped after a tip-off, The Sun reported.
Police said searches of the premises and a residential address in the Newcastle area were also carried out.