A strong earthquake with a preliminary magnitude of 6.9 has hit south-western Japan, the country's meteorological agency said on Monday.

Tsunami warnings were issued for Miyazaki Prefecture, where the temblor was centred, in the southwestern island of Kyushu, as well as nearby Kochi Prefecture, shortly after the quake struck at 9.19p local time, according to the agency.

"Tsunami can strike repeatedly. Please do not enter the sea or go near coastal areas," the agency said on X.

The extent of damage was not immediately clear. (AP/AFP)