Seven men, at least three of them of North African origin, are being questioned by anti-terrorism police after early morning arrests in Edinburgh and London. All of the detained men are in their early thirties.
A spokesman for Lothian and Borders police in Scotland confirmed the arrests. The seven men have been detained under the Terrorism Act 2000 and will be held at a secure location while inquiries continue.
The arrests follow Monday's arrests by French police of four suspects and the seizure of two small containers of unidentified chemicals and a protective suit against chemical or biological arms during a raid in a northern Paris suburb.
French Interior Minister Nicolas Sarkozy said one of the suspects had links with Rabah Kadre, one of three North Africans already being held in Britain on terrorism-related charges.
The British government has played down media speculation that Kadre, 35, and two others could have been planning a gas attack on the London underground rail network.