An undersea earthquake measuring 5.4 on the Richter scale hit south of the Greek island of Hydra late Friday and was felt in the capital, the Athens Observatory said.

There were no immediate reports of casualties from the quake, which struck at 20:08 GMT, 89 kilometres (55 miles) south of Athens and 111 kilometres deep. The US Geological Survey said it had a magnitude of 5.7.

The quake could be felt as far south as Crete. In Hydra, an island in the Aegean, some worried residents left their houses, while police were dispatched to assess the damage.

Earthquakes occur frequently in Greece. In January, thousands of people were left homeless by a quake on the Ionian island of Cephalonia, to the west of the country.