South Korean and Japanese coast guards launched a joint probe into a South Korean fishing boat's possible violation of Japanese waters near the disputed islets of Dokdo, known as Takeshima in Japan, late Thursday, according to Seoul's coast guard.

Patrol ships of the both sides began the joint investigation at around 3:53 p.m. local time in waters about 36 sea miles southeast off the disputed islets in the Sea of Japan, to find out whether a 29-ton South Korean fishing boat intruded into Japan's exclusive economic zone, Korea Coast Guard said in a press release.

Earlier reports said a South Korean coast guard vessel have involved in a confrontation with four Japanese patrol ships as of 2:00 p.m. local time.

Seoul's coast guard dispatched the patrol vessel to conduct joint investigation with the Japanese side after the receiving report from the fishing boat "SSangyong", which was chased by Japanese coast guards' ships when it was sailing in waters about 42 sea miles southeast off Dokdo earlier in the day and then sailed back toward South Korean side, the press release said.

The incident will be treated in accordance with the relevant laws if the possible violation is confirmed, it added.

Both South Korea and Japan claim sovereignty over the lonely islets, lying halfway between the two countries. South Korea has controlled the islets since 1950s.