A 36-year-old man has been arrested in connection with the failed 21 July London bombings.
The 21 July attacks in London failed
The man was arrested by anti-terrorist officers on suspicion of assisting an offender and alleged immigration offences, Scotland Yard said.
He was taken to a London police station where he remains in custody.
Four men have been charged with attempted murder and conspiracy to murder following the attacks. A fifth man faces the conspiracy charge.
The man arrested on Tuesday was held at about 1705 BST, Scotland Yard said.
The failed 21 July attacks took place two weeks to the day after four suicide bombers killed 52 passengers on the London transport network.