Greek anti-terrorist police arrested three people late on Wednesday after weapons and explosives were discovered in separate locations in the district of Koukaki, Athens.
Police say that the three suspects, known for their connections to extremist groups, were two men, aged 38 and 42, and a 36-year-old woman.
One of the suspects is said to have been involved in the recent kidnapping of a businessman in Thessaloniki.
Police say the operation is ongoing.