The case, according to police officials, is linked to anti-establishment guerrilla groups. Anti-terrorism police suspect the blast occurred while the bomb was being made, Reuters reported.
The Greek man arrested had testified regarding the case on Friday night. According to police sources, he said he shared the keys of the flat with the couple involved in the blast but denied any involvement in the explosion.
He is expected to appear before a prosecutor later on Saturday.
Several left-wing and anarchist guerrilla groups, declaring war on all forms of governments, have emerged in Greece over the past two decades after the dismantling of its most lethal group, “November 17.”
Small bomb and arson attacks against politicians, police, judges and businesses were frequent during the country’s 2009-18 debt crisis. They have abated in recent years but still occur.