Athens  - Unknown assailants fired two shots at a police bus in Athens Tuesday morning, according to Greek radio broadcasts.

No injuries were reported in the incident, which occurred in the Athens suburb of Goudi. One shot hit a tyre while the second hit the side of the vehicle. The bus driver managed to bring the bus to a safe halt, the broadcasters reported.

Separately, unknown individuals set fire to four cars and a motorcycle in various parts of Athens overnight.

Athens has been subjected to sporadic violent protests ever since the police shooting of a 15-year-old boy on December 6. (dpa)