Searches are ongoing at five houses in Burnley
Police have been granted extra time to question three men arrested as part of a counter-terrorism operation.
Nine men were stopped by police on the M65 near Preston, Lancashire, on Friday night and arrested as part of an ongoing intelligence-led investigation.
Six of the men were later released without charge, but three men, aged 26, 29 and 36, remain in custody.
Police are also searching five houses in Burnley and three vehicles which were seized.
The vehicles had been making their way to London to join a Gaza aid convoy when they were stopped on Friday.
A Lancashire Constabulary spokeswoman said: "Searches are ongoing at five houses in Burnley and three vehicles seized as part of the operation are also being searched as a priority in order to release them as soon as possible so they can continue on to their destination."
Residents in the areas where the searches took place received a note through their letterboxes from Lancashire Constabulary informing them about the operation.
The letter assured people that the searches would be conducted "with sensitivity" and asked for support during the investigation.
Police said officers now have until Thursday to question the three men.