South Korea has reiterated its position on a December 2018 incident, saying its military vessel did not level fire-control radar at a Japanese patrol aircraft over the Sea of Japan.

It stressed that the vessel was using radar to search for a drifting North Korean ship. Japan has been saying that the destroyer directed fire-control radar at the Self-Defense Force plane.

A spokesperson for South Korea's defense ministry told a news conference on Thursday that Seoul and Tokyo disagree on the issue.

The spokesperson also said defense authorities from both countries need to discuss the matter while closely monitoring how bilateral relations will develop.

Vice defense ministers from Tokyo and Seoul agreed in September this year to hold working-level discussions on the incident.

Analysts are closely watching how the issue will affect bilateral efforts to boost cooperation amid tensions heightened largely by a series of ballistic missile launches by North Korea.