The last time Russian military aircraft circled Japan was in 2019, a ministry official told AFP on Friday, but that incident involved bombers that did enter the nation's airspace.

From Thursday morning to afternoon, the Russian Tu-142 aircraft flew from the sea between Japan and South Korea towards the southern Okinawa region, a defence ministry statement said.

They then went northwards over the Pacific Ocean to finish their journey off northern Hokkaido island, it added.

The planes also flew over an area subject to a territorial dispute between Japan and Russia, the official said.

"In response, we mobilised Air Self-Defence Force fighter jets on an emergency basis," the ministry statement said.

Earlier this week, Russian and Chinese warships began joint drills in the Sea of Japan.

The drills are part of a major naval exercise that Russian President Vladimir Putin has described as the largest of its kind in three decades.