There were no initial reports of injuries or serious material damage after a 6.1-magnitude earthquake struck under the Mediterranean seabed east of the Greek island of Crete on Thursday, local authorities said.

The tremor happened shortly after 1800 GMT, the US Geological Survey said.

The quake's epicenter was 20 kilometres (around 13 miles) below sea level, 50 km east of the island on the Cretan-Rhodes ridge, where the African tectonic plate meets the Eurasian plate.