Tokyo - A moderate 5.8-magnitude earthquake struck off the east coast of the Japanese island of Honshu early on Saturday, seismologists said, but there were no immediate reports of casualties or damage.

The tremor hit at 02.32 am (1732 GMT on Friday, 1.32am Singapore time) with an epicentre 192 kilometres (119 miles) east-southeast of Tokyo at a relatively shallow depth of 18 kilometres, the US Geological Survey said.

There was no immediate tsunami alert.

Around 20 per cent of the world's most powerful earthquakes strike Japan, which lies near the junction of two tectonic plates.

Geologists warn that Japan is overdue for a massive and potentially devastating earthquake.

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