Police investigating attacks on mainland Britain by the so-called Real IRA were this evening granted more time to question a 35-year-old man.
The man can be quizzed at a West Yorkshire police station until Monday, while police search three residential addresses and a farm in Derbyshire and Nottinghamshire.
The head of the Anti-Terrorist Branch, Deputy Assistant Commissioner Mr Alan Fry, has said: "This is part of the ongoing investigation into the Real IRA attacks starting with Hammersmith Bridge in July 2000. He was arrested on suspicion of involvement in terrorism."
Detectives initially had 48 hours to question the man, who is of Irish origin, but can apply for extensions of up to one week under the Terrorism Act.
A Scotland Yard spokesman said: "The operation is ongoing and we are not in a position to confirm further details at this stage."
Locals near the farm in Derbyshire said the area is quiet, friendly and close-knit. They said the police presence - and the arrest - had come as a shock.
A neighbour said the man had only recently married and had invited him to his wedding at a local club.
PA