TOKYO - AN earthquake measuring 6.6 on the Richter scale shook northern Japan on Saturday, the meteorological agency said, issuing a warning of a minor tsunami in the region.

There were no immediate reports of casualties or damage.

The tremor struck at 11.39 am (10.39am Singapore time) with its epicentre located in the Pacific off Fukushima prefecture at a depth of 10 kilometres, the agency said.

Tsunami tidal waves some 50 centimetres high may shortly hit coastal areas in Miyagi and Fukushima prefectures, north of Tokyo, the agency added. -- AFP