TOKYO, Dec. 28 (Xinhua) -- The Japanese Defense Ministry on Friday released video footage of an incident last week in which a South Korean warship locked radar on a Japanese patrol plane.

The ministry has said that a South Korean Navy ship directed fire-control radar at a Japanese Maritime Self-Defense Force (MSDF) P-1 patrol aircraft off the coast of Ishikawa Prefecture, central Japan, around 3:00 p.m. local time on Dec. 20.

In the 13-minute-long footage taken by the Japanese patrol plane, the South Korean warship locked fire-control radar at least twice.

One of the crew members of the Japanese MSDF P-1 plane talked to the destroyer in English three times through different frequencies in order to confirm its intention.

"This is Japan Navy. We observed that your FC (fire-control) antenna is directed to us. What is the purpose of your act?" A crew member said in the footage.

The video was posted on the official website of the Defense Ministry after it was shown to the South Korean side.

"It was an extremely dangerous act that could cause a contingency situation," Japanese Defense Minister Takeshi Iwaya has said.

South Korea has denied such action, saying that the warship was on the spot to rescue a fishing boat from the Democratic People's Republic of Korea in distress and used an optical camera.

South Korea's defense ministry on Friday expressed deep concern and regret over Japan's release of the video footage.