(Reuters) - An earthquake with a magnitude of 6.1 struck in the early hours of Wednesday to the southeast of Japan's main island of Honshu, the U.S. Geological Survey said.

The quake had a depth of 33 km and occurred nearly 400 km (250 miles) from the Izu islands just southeast of Honshu. There were no immediate reports of a tsunami or of any damage.

(Reporting by Gareth Jones; Editing by Mark Trevelyan)