A strong undersea earthquake with a preliminary magnitude of 6.4 jolted the far north of Japan and Russia's far east early on Sunday, a Japanese government agency reported, but there were no immediate reports of damage.

There was no threat of tsunami from the quake at 4:19 a.m. (1919 GMT). It centred in the remote and sparsely populated Kuril Islands northeast of Hokkaido, the Japan Meteorological Agency said on its website (www.jma.go.jp).

The quake was centred 290 km (180 miles) east-northeast of Kuril'sk in the Kuril Islands and around 1,515 km (940 miles) northeast of Tokyo, said the U.S. Geological Survey, which recorded the magnitude at a similar 6.6.