The Japan Meteorological Agency issued on Thursday its first-ever warning of the risk of a huge earthquake on the country's Pacific coast, following one of magnitude 7.1 that struck the southwestern island of Kyushu the same day. 

"I have decided to stay in the country for the next week or so to ensure our preparations and communications are in order," Kishida told a press conference, although the warning did not give a timeframe or call for evacuations.

"But it is the first time it is issued and I believe people would be feeling anxious about it," he added.

"Consequently, I have decided to cancel my planned visit to Central Asia and Mongolia."

The government may seek to hold the meetings with regional leaders online instead, public broadcaster NHK said. The visit to Kazakhstan, Uzbekistan and Mongolia was originally set to run from Friday to Monday. 

The meteorological agency's advisory warns of a higher probability of a huge earthquake in the Nankai trough, an ocean-floor trench running along Japan's Pacific coast, where previous quakes have triggered enormous tsunamis.

It did not indicate a quake would definitely happen, but encouraged people to be ready to evacuate if necessary.

Japan estimates at 70 percent to 80 percent the probability of an earthquake of magnitude 8 or 9 happening around the trough in the next 30 years, according to the infrastructure ministry.