Three men arrested in connection with a series of bombings in London last July will be questioned by police today.
Under new anti-terror laws, police can hold them for a maximum of 28 days.
The three, all understood to be from Leeds, were taken to London's top-security Paddington Green police station after they were arrested yesterday afternoon.
Two of the men - aged 23 and 30 - were arrested at Manchester Airport as they prepared to board a flight to Pakistan. They had gone through passport control and were in the terminal building at the time of the arrests.
The third man, aged 26, was held at his home in Leeds.
Officers also searched houses in Leeds, where three of the July 7th bombers had strong connections.
The attacks in 2005 that killed 52 saw four suicide bombers detonate rucksack devices on three Tube trains and a bus.