A 27-year-old man has been arrested in connection with the London bomb attacks of 7 July which killed 52 people.
All four suicide bombers are said to have died in the blasts
Anti-terrorist branch officers picked the suspect up in Dewsbury in West Yorkshire. Officers are searching two residential addresses in the area.
The man is being held on suspicion of commission, preparation or instigation of acts of terrorism and is being quizzed at a local police station.
The arrest follows a tip-off by the News of the World newspaper.
The Metropolitan Police said in a statement: "We thank the News of the World for bringing this matter to our attention and material passed to police by the newspaper is now being assessed by the Metropolitan Police anti-terrorist branch."
A spokesman added that the arrest had been prompted by alleged comments the man made in the newspaper.
The arrest comes three and a half months after the co-ordinated attacks on the London's transport network.
Three suicide bombers blew themselves up on three central London Tube trains at Russell Square, Aldgate and Edgware Road.
A fourth bomber blew up a London bus at Tavistock Square.
The police investigation into who may have aided or directed the bombers is continuing.
In September, a video statement from one of the London suicide bombers, Mohammad Sidique Khan, strongly suggested a link between the bombers and al-Qaeda.
The latest suspect is the only man being held in connection with the attacks of 7 July although several others have been arrested and released without charge.