A tsunami alert was issued for the Mediterranean coast early on Friday following a 6.8-magnitude earthquake off the coast of Greece, the European-Mediterranean Seismological Centre said in a Twitter message.

"Sea level changes observed in Greece confirming TSUNAMI," the message reads.

At the moment, the tsunami waves are about 20 cm in height, but they can grow as they approach the coast. EMSC experts warned local residents to stay away from beaches.

According to the DPA news agency, jolts were felt all across Greece, prompting people to leave their homes.

The epicenter of the quake was located 287 km west of the Greek capital Athens, at the depth of 10 km. A series of aftershocks followed.

According to EMSC, the tremor was also felt in eight other countries - Albania, Bosnia and Herzegovina, Bulgaria, Italy, Macedonia, Libya, Turkey and Malta.