* Undersea earthquake described as "severe"
* No serious damage or casualties
* Tremor was felt in Athens, 180 miles away (Adds witness, Athens Geological Institute and quotes)
ATHENS, Oct 12 (Reuters) - An earthquake of 6.4 magnitude off the coast of Crete caused minor damage on the Greek island on Saturday, but there were no reports of casualties or serious destruction, police and fire brigade said.
The centre of the quake, at 1311 GMT, was 22.5 miles (40 km) below the seabed and 43 miles (70 km) west of Chania on Crete, the U.S. Geological Survey said.
Tremors were felt as far as the Greek capital Athens, some 180 miles (275 km) away, and across southern Greece, including the Peloponnese peninsula and the Cyclades cluster of islands, the Athens Geological Institute said.
It put the quake at a lower 6.2 magnitude but described it as "severe".
Greece is often rocked by earthquakes. Most cause no serious damage but a 5.9 magnitude quake in 1999 killed 143 people.
Local media in Crete said the quake caused minor damage to shops and houses in Chania.
"It was big. We were rattled a lot and the lights were swaying back and forth," resident Katerina Zaharioudaki told Reuters by telephone from Crete's capital Heraklion.
"It was much stronger than the earthquakes we're used to and it lasted several seconds," she said.
Efthimios Lekkas, a geology professor in Crete, told Greek TV that the characteristics of the quake, and the fact that it did not immediately appear to have caused serious damage, indicated that it was quite deep. (Reporting by Angeliki Koutantou and Karolina Tagaris; editing by Andrew Roche)