A powerful earthquake measuring 6.5 on the Richter scale hit the Peloponnese region of southern Greece early this morning, the geodynamics institute of the Athens observatory reported.
Police said there were no immediate reports of casualties or serious damage.
The observatory said the epicentre of the tremor, which struck at 7.14 am (5.14 Irish time), was near the village of Leonidio in the southeast Peloponnese, around 150km southwest of Athens.
'The tremor occurred at a depth of more than 70 km and that is why there have been no casualties,' observatory spokesman Yannis Drakatos said.
The quake was particularly felt in the Greek capital and in the south of the country, where many residents were woken up and went out into the street.
The Italian civil protection authority in Rome said the quake was also felt throughout southern Italy.
Greece is the European country most prone to earthquakes, with seismic activity there accounting for half of the continent's tremors.
The last serious earthquake in Greece was in September 1999, when more than 100 people were killed. Its epicentre was 60km west of Athens and it registered 5.9 on the Richter scale.