An earth tremor of magnitude 5.7 has struck 185 kilometres south-south-east of Japan's Izu islands on Saturday, the United States Geological Survey has said.

The USGS at first put the quake at 6.1, but later revised it to a weaker reading. Japanese authorities put the magnitude of the quake at 5.9.

The tremor was at a shallow depth of 10 kilometres.

Tsunami warnings were lifted for the Izu and Ogasawara islands after they experienced small waves following the earthquake, public broadcaster NHK said.

Tsunamis of up to 50 centimetres were recorded in the islands stretching south of Tokyo, before the Japan Meteorological Agency lifted warnings at 4:10 am local time, NHK said.

Reuters