South Korea's KDX-1 class destroyer locked its fire control radar on a Japanese P-1 patrol plane on Thursday off Noto peninsula in the Sea of Japan that divides the two countries, Tokyo's defence ministry said.

"It was an extremely dangerous act," defence minister Takeshi Iwaya told reporters.

"Considering the significance of this case, our country today conveyed a strong protest to South Korea."

Ties between Japan and South Korea -- both allies of the US -- have remained icy for decades due to the legacy of Japan's brutal 1910-45 colonial rule of the Korean peninsula.

Both countries have frequently locked horns over islets in the sea controlled by Seoul but also claimed by Tokyo.

Japan cancelled plans to join an international naval fleet review in South Korea in October after Seoul demanded the removal of a controversial naval flag hoisted by a Japanese vessel.

Two years ago, Tokyo and Beijing were at loggerheads over accusations Japanese warplanes locked their fire control radar onto Chinese aircraft.