Three people were detained by counter-terrorism officers during a raid in an apartment in central Athens on Wednesday morning, according to Greek media citing an activist website.
The operation is linked to the arrest of two Greek nationals in Edinburgh on June 15 in connection with a suspicious package left in the centre of the city in January 2018.
According to police sources, officers are investigating a possible link between the 35-year-old man and 32-year-old woman arrested in Scotland and an anarchist group operating in Athens.
One of the suspects in the Athens raid was later released, the same website said. No official announcement has yet been issued by Greek Police.
The Greeks arrested in Edinburgh were described as a couple in the local press which reported that they were picked up at separate locations in the Capital.
The incident in 2018 sparked a major police response in a public shelter in the gardens where the suspicious package was found. Army bomb disposal experts carried out a controlled explosion of the box.