A strong earthquake of preliminary magnitude 6.0 shook the eastern Russian province of Sakhalin, rattling parts of northern Japan early on Friday, but there were no immediate reports of damage or injuries, Japan's weather agency said.
There was no fear of a tsunami - huge waves caused by undersea disturbances or volcanic activities - from the 12:26 am (2056 IST,) temblor, the Meteorological Agency said in a statement.
The quake struck in Russia's Sakhalin province, about 1,242 kilometres north of Tokyo, and was centred about 10 kilometres under the earth's surface, the agency said.
Tremors were felt in parts of Japan's northern Hokkaido prefecture. Prefectural police spokesman Takashi Takakura said there were no reports of injuries or damage in Hokkaido.
Japan and Russia's Far Eastern provinces form part of the Pacific Ocean's "Ring of Fire." Japan sits atop four tectonic plates and is one of the most earthquake-prone countries in the world.