ATHENS (Reuters) - A quake of magnitude 5.2 struck off western Greece late on Saturday, Athens' Geodynamic Institute reported, but there were no immediate reports of damage or casualties. The quake's epicentre was 12 km (8 miles) northwest of the city of Ioannina, said an official at the Institute. Greece and the surrounding region is often rattled by earthquakes at sea, most causing no serious damage. (Reporting by Angeliki Koutantou; Editing by Kevin Liffey)