A strong earthquake has struck southern Greece, shaking buildings over an area from the southern Peloponnese region to the capital, Athens.

The earthquake struck at about noon (1000 GMT) and geologists said its magnitude was between 6.5 and 6.7.

Seismologists said the epicentre was beneath the seabed off Kalamata, about 230km (140 miles) south of the capital.

Witnesses in Athens said it lasted at least 15 seconds, and there were no reports of casualties or damage.

"We were shaken for quite a long time, swaying back and forth," Tanya Spiropoulou from the northern Athens suburb of Marousis told Reuters news agency.

A farmer in Kalamata told the agency that the quake "was not as strong as other times, but we felt it".

Seismologists said aftershocks were possible, and Greek television stations warned people in areas near the epicentre, to stay away from buildings.

The tremor was felt as far away as Cairo, in Egypt.

Earthquakes are common in Greece, and the last serious earthquake there killed more than 100 people in September 1999.