A strong earthquake registering 6.5 on the Richter scale shook many parts of Greece Sunday, but there were no immediate reports of injury or major damage, seismologists at the Athens Geodynamic Institute said.

The earthquake occurring at 7:14 am (0514 GMT) had an epicentre approximately 60 kilometres north-east of the southern town of Kalamata near Leonidio, southwest of Athens in the southern Peloponnese region.

The quake, which was recorded to have occurred at a depth of 80 kilometres, wakened residents in Athens and caused panic in rural areas as villagers ran out onto the streets.

Panicked residents on the southern Mediterranean island of Crete and on dozens of Aegean islands called television stations saying they were woken up.

No injuries were reported by officials even though boulders had fallen onto roads near Leonidio. Minor damage was reported to several homes in the southern Peloponnese.

The Deputy Mayor of Leonidio, Llias Manos, said there was panic among residents, but no one was injured or suffered serious damage.

"Unlike the majority of earthquakes in Greece this one occurred deep underground, which explains why there was no major damage," institute director Gerasimos Papdopoulos was quoted as saying, adding that he expected little aftershock activity.

The US Geological Institute said the quake had a preliminary magnitude of 6.1.