Assailants fired early Monday at least nine shots at the Athens headquarters of New Democracy, the main party in Greece’s ruling coalition, prompting a fresh dispute between the country’s politicians about politically related violence.

One of the shots fired at around 2.30 a.m. from a Kalashnikov assault rifle hit the office of Prime Minister Antonis Samaras, who has led New Democracy since 2009. The bullet smashed through the window and left a mark on the wall.

There were no injuries as the building was empty at the time.

The party’s headquarters are located on Syngrou Avenue in southern Athens and police found a burnt out car a few kilometres away in the suburb of Palaio Faliro.

Officers believe the vehicle, reported stolen, is linked to the attack as the fire brigade was called to the scene at about 3 a.m., shortly after the raid on ND’s headquarters.

“Democracy, New Democracy and the country’s Prime Minister Antonis Samaras cannot be terrorized,” said the secretary of ND’s political committee, Manolis Kefaloyiannis.

The attack on the party’s offices came a day after assailants set off an incendiary device at the home of government spokesman Simos Kedikoglou’s brother. Nobody was injured in that attack even though Giorgos Kedikoglou was at home with his family when it occurred.

Several New Democracy and PASOK offices around Athens were also firebombed over the weekend. A total of 17 incendiary attacks, including on a SYRIZA office in Iraklio, Crete, were recorded over the weekend.

Early on Friday, the homes of five journalists were the subject of attacks. Again, there were no injuries. A group called Militant Minority claimed responsibility for the attack. The organization also claimed an attack on the home of ex-Finance Minister Yiannos Papantoniou in December.

The spate of attacks, as well as police operations to clear squats in central Athens, have been at the center of a full-blown political row between the coalition parties and SYRIZA, which has been accused of having an equivocal stance on the use of violence – a charge that the leftists vehemently deny.

“The difference between inflammatory statements and inflammatory attacks is very small,” said Simos Kedikoglou early on Monday. “There has to be a clear denouncement of violence and verbal violence.”

Kedikoglou added that he had received threatening phone calls recently.

SYRIZA spokesman Panos Skourletis said the party’s condemnation of recent attacks was a “given”. He accused New Democracy of trying to polarize the political climate in order to draw attention from austerity measures and the state of the economy.

He referred to the assailants as “useful idiots” and said that ND was creating a “civil war climate.”

SYRIZA leader Alexis Tsipras is reported to have called Samaras to ask for a full and thorough investigation into the attack on ND's headquarters.