TOKYO - Japan's weather agency on Wednesday downgraded a tsunami warning for islands of the southern Okinawa prefecture to a tsunami advisory, while still urging people there to stay away from coastal areas.

A 30-centimeter tsunami was observed at the island of Yonaguni at 9:18 am local time, while small waves of 20 centimeters also reached Ishigaki island and Miyakojima island, according to the Japan Meteorological Agency (JMA).

Weather officials warned of the possibility of larger tsunami of up to 3 meters in the region, urging residents in affected areas to evacuate to higher ground or safe places as soon as possible.

This was the first time the JMA issued a tsunami warning for the coastal areas of Okinawa prefecture since the 2011 Great East Japan Earthquake and Tsunami.

Flights were suspended at the prefecture's main Naha airport following issuance of the tsunami warning, with passengers urged to move to higher floors of the terminal building, its operator said. The airport is located on the coast of the main island of the prefecture.

The tsunami warning was issued after a 7.3-magnitude earthquake jolted the sea area near Hualien of China's Taiwan earlier in the day.