An earthquake with a preliminary magnitude of 5.1 has struck northern Greece, but no injuries or damage have as yet been reported, according to UKPA.

The Athens Geodynamic Institute said the undersea earthquake occurred at 3.34am local time, 151 miles north of the Greek capital, off the coast of the northern peninsula of the Athos monastic community.

Greece is in one of the world's seismically active areas, with hundreds of quakes occurring each year. The vast majority cause no injuries.