A 35-year-old Irishman has been arrested in Britain on suspicion of being involved with the so-called Real IRA.
He was held at a house in Derbyshire and police are searching three homes and a farm in Derbyshire and Nottinghamshire.
He is being questioned at a West Yorkshire police station.
Head of the Anti-Terrorist Branch, Deputy Assistant Commissioner Mr Alan Fry, said: "This is part of the ongoing investigation into the Real IRA attacks starting with Hammersmith Bridge in July 2000.
READ MORE
"He was arrested on suspicion of involvement in terrorism."
Detectives will have 48 hours to question him but will be able to apply for extensions of up to one week under the Terrorism Act.
PA
