Unidentified attackers have opened fire on the headquarters of Greece's governing New Democracy party with an assault rifle, in what the government says is a worrying escalation in political violence.
Police say a bullet pierced the window of an office the Prime Minister maintains in the building, but no-one was hurt, Reuters reports.
The gun assault on Monday follows a spate of makeshift bomb attacks against journalists and political figures in the past week.
Some of the attacks have been claimed by leftist groups angry at Greece's deep financial crisis.
Reuters reports political violence is not uncommon in Greece but deadly attacks are rare.