ATHENS (REUTERS) - An earthquake of magnitude 6.1 struck around 50km off the eastern tip of the Greek Mediterranean island of Crete, the US Geological Survey said.

USGS located the quake 152km east-southeast of the island's main town, Heraklion.

It revised the magnitude from a previous 6.3.

Greek fire brigade officials in Athens said the quake had been felt on the island but that there were no immediate reports of damage or casualties.

A local police official in Crete said the quake had been strong enough to send some of the island's residents rushing into the streets.