Japan Meteorological Agency says a powerful earthquake occurred off the northern Japanese coast Sunday, and a tsunami advisory has been issued.

The JMA said that the earthquake with a preliminary magnitude of 6.7 occurred off the coast of the Iwate prefecture at the depth of 10 kilometres below the sea surface.

The agency issued an advisory for a tsunami of up to 1 metre along the northern coastal region.

A tsunami was observed 70 km (45 miles) off the coast of Iwate Prefecture at 5:12 p.m. (0812 GMT) and was expected to reach the Pacific coastline soon, NHK said. The wave was expected to be about 1 metre (3 feet, 3 inches), it said.

An earthquake of magnitude 6.26 earlier struck off the east coast of Japan's largest island, Honshu, which includes Iwate, according to the US tsunami warning system.