An earthquake with a preliminary magnitude of 4.2 jolted eastern Japan on Thursday morning, the Japan Meteorological Agency said.

Buildings shook in Tokyo, but there were no reports of damage and no tsunami warning was issued after the quake.

The focus of the tremor was 80 km (50 miles) below the surface of the earth in Saitama prefecture, just north of the capital.

Japan is one of the world's most earthquake-prone countries, with a tremor occurring at least every five minutes. Every year there are up to 2,000 quakes that can be felt by people.

In October 2004, an earthquake with a magnitude of 6.8 struck the Niigata region in northern Japan, killing 65 people and injuring more than 3,000.

That was the deadliest quake since a magnitude 7.3 tremor hit the city of Kobe in 1995, killing more than 6,400.