A second man arrested after potentially explosive materials were seized at a house in Goole, East Yorkshire is to be detained for a further seven days.
The 31-year-old from Goole was arrested under the Terrorism Act in the Dundee area of Tayside on Saturday.
A court has approved a warrant to detain him for a further seven days.
Another 31-year-old man remains in custody. Both are being questioned by Counter Terrorism Unit (CTU) officers in Leeds.
Both are being held pending further inquiries and the results of forensic tests, police said.