The quake took place at 11:57 pm (1457 GMT) with the focus located in the Pacific Ocean off central Japan, the agency said.

It warned of waves of up to one metre for coastal areas in western and central Japan, with some reaching Wakayama prefecture.

Waves of 86 centimetres (34 inches) were observed in Kushimoto, Wakayama prefecture, public network Japan Broadcasting Corp. said.

It followed a quake with the magnitude of 6.8 on the Richter scale that shook western Japan at 7:07 pm.