A strong magnitude 6.1 earthquake struck off western Greece early on Monday, the United States Geological Survey said.

The quake, which was initially reported as 6.4 in magnitude, struck 76 miles (122 km) west of Patras at a relatively shallow depth of 8.5 miles (13.7 km) at 0308 GMT, as reported by Reuters.

There were no immediate reports of injuries or damage.