Gunmen shot at the headquarters of the ruling New Democracy Party near the center of Athens Monday. There were no casualties.

"At around 3 a.m. (0100 UCT) security guards saw two men come out of a black car and open fire with a Kalashnikov on the building, which was empty at the time in question. A bullet went through the window of the political office of the prime minister, Antonis Samaras, and nine rounds of ammunition were found on the ground," said a police officer.

A spokesman for the Greek government, Simos Kedikoglou, speculated that the attack was a symbolic one directed against Samaras.

"It is a new and worrying escalation from those who want to spread terror in our society," he said.

German Finance Minister Wolfgang Schäuble is scheduled to meet Greece's left-leaning opposition leader, Alexis Tsipras, in Berlin later on Monday.

sej/msh (Reuters, AP)