Tokyo, Apr 28 (IANS): An earthquake with a preliminary magnitude of 5.6 struck Japan's northernmost Hokkaido prefecture on Sunday, the Japan Meteorological Agency (JMA) said.

According to the JMA, the earthquake, which occurred at 2:25 a.m. local time, was centred in the Tokachi-chiho Nambu region in Japan's northernmost prefecture, with its epicentre at 42.5 degrees north latitude and 142.9 degrees east longitude, Xinhua reported.

The quake occurred at a depth of 110 km, the weather agency said, but no tsunami warning or advisory was issued as a result of the temblor, said the JMA.

The earthquake logged 4 on Japan's seismic scale, which peaks at 7 in multiple regions in Hokkaido, the JMA added.

The weather agency also said the quake registered 3 in the neighbouring prefecture of Aomori, south of Hokkaido, in Japan's Tohoku region.

There have been no immediate reports of major damage or injuries as a result of the quake, according to local authorities as well as local media accounts.

Japan's nuclear watchdog has not reported any abnormalities at nuclear power plants possibly affected by the quake, and, specifically, Hokkaido's sole Tomari Nuclear Power plant's operator Hokkaido Electric Power Company, has not reported any irregularities at the plant, located in the town of Tomari in Hokkaido's Furuu District.