A powerful 8.9-magnitude earthquake has struck off Japan's northeastern coast Friday, triggering a tsunami as high as 10 metres, leaving at least five people killed and several injured, early reports said.

The US Geological Survey said the epicenter was about 250 miles from Tokyo at a depth of 20 miles. They earlier estimated the quake to be of 7.9 in magnitude but later revised it to 8.9 on Richter scale.

The Japan government has confirmed at least five deaths and there were reports of several injuries, including in Tokyo, hundreds of miles from the epicenter.

Prime Minister Naoto Kan said the quake caused major damage in broad areas.

This is a rare major quake, and damages could quickly rise by the minute, local media reported, quoting Junichi Sawada, an official with Japan's Fire and Disaster Management Agency.

The tremors were felt all over Japan including Shizuoka-ken where houses swayed for two to three minutes, while the local TV channels showed fires in some places.

Japan is one of the world's most seismically active areas and accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater. The country's worst previous quake was in 1923 in Canto that killed more than 140,000 people.