A 33-year-old Algerian man is due to appear before a prosecutor on Monday after being arrested over the weekend as part the investigation that followed a raid on a suspected Islamist cell in Belgium a few days earlier.
Greek and Belgian authorities have said that they do not believe the man in question is the alleged mastermind that communicated with cell members in Belgium from a mobile phone in Greece.
Nevertheless, Belgian authorities have asked for the Algerian to be extradited for further questioning. He was one of four people detained in Athens on Saturday.
Two suspected terrorists were killed and one arrested during a police raid in the town of Verviers last week.