South Korea's Navy warship used an optical camera to identify an approaching Japanese patrol aircraft last week, military sources said Sunday, rejecting Tokyo's claim that it had directed its fire-control radar at the plane.

The sources also said that the warship's tracking radar system was in operation while the camera was on, but it did not send out any radar beam directly toward the Maritime Self-Defense Force's P-1 patrol aircraft.

Diplomatic tensions spiked after Japan claimed that the South's Gwanggaeto the Great destroyer targeted the Japanese plane on Thursday. Seoul said that Tokyo misunderstood its naval operation to help a North Korean ship drifting near a sea border.

"Though a radar system was in operation at that time, there wasn't any radar beam sent out toward the Japanese aircraft," a military source said on condition of anonymity. "We make it clear that there wasn't any act on our part that threatened the Japanese maritime patrol aircraft."

Seoul's Ministry of National Defense has rejected Tokyo's claim, saying that it has already explained its position to Japan and will strive harder to ensure that there will not be any "misunderstanding."

Critics here raised speculation that politicians in Tokyo appear to be using the incident to divert attention from the government's waning public support. (Yonhap)