UPDATE 1- Strong earthquake jolts northern Japan, felt in Tokyo

TOKYO, March 14 (Reuters) - A strong earthquake with a preliminary magnitude of 6.6 jolted northern Japan on Sunday, seismologists said, shaking buildings in the capital Tokyo some 240 km (150 miles) away.

There were no immediate reports of injuries or damage and no tsunami warning was issued. The magnitude of the quake, at 5:08 p.m. (0808 GMT), was measured at 6.6 by the U.S. Geological Survey and the Japan Meteorological Agency (JMA).

The epicentre was about 40 km (25 miles) beneath the ocean off Honshu, Japan's main island, the JMA said.

Tokyo Electric Power Co Inc (TEPCO) said its two nuclear power plants in the region were operating normally. Tohoku Electric Power Co said operations at its Onagawa nuclear power plant were also normal.

Public broadcaster NHK said a bullet train in the area automatically halted for a brief time but soon resumed operating.

Japan is one of the world's most earthquake-prone countries, with a tremor occurring at least every five minutes.

(Reporting by Chikafumi Hodo and Yoko Kubota; Editing by Paul Tait)

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