The Chinese Consulate General in Japan's Fukuoka City alerted Chinese citizens living Okinawa to a possible tsunami after a warning was issued for coastal areas of Okinawa on Wednesday.

The Japan Meteorological Agency (JMA) downgraded its tsunami warning for Japan's southern islands to a "tsunami advisory" on Wednesday after a powerful earthquake hit Hualien County, in China's Taiwan region. 

The JMA said waves as high as one meter could hit the region following the earthquake. It had previously warned of an estimated maximum tsunami height of three metres. "Please avoid going near or into the sea until the advisory is lifted," a JMA official said.

(With input from AFP)