A 46-year-old man has been arrested in Liverpool by detectives investigating loyalist paramilitaries connected to Northern Ireland.
The man was arrested at 6.30am in Liverpool by officers from the Greater Manchester Police Anti-Terrorism Unit.
He was held "on suspicion of involvement, commissioning and instigation of acts of terrorism", according to police.
A spokesman said: "The arrest is part of ongoing investigations into Irish loyalist terrorism and is not linked to the explosions in London.