South Korea started early Monday its research mission which is to survey ocean currents around a set of disputed islets controlled by South Korea but also claimed by Japan, Kyodo News reported.

The some 2,500-ton research vessel, dubbed "Ocean-2000", has departed from the Busan port in the morning, according to news reaching here.

On the same day, Japanese Chief Cabinet Secretary Shinzo Abe once again urged South Korea to exercise "self-restraint" on survey around the islands, which are known as Takeshima in Japan and Dokdo in South Korea, in the Sea of Japan.

Abe called on South Korea to make a "sensible decision", and warned that Japan will take "appropriate" action based on the U.N. Convention on the Law of the Sea and other relevant domestic laws if South Korea begins the research, Kyodo said.

The South Korean government said the survey, including water currents research around the disputed islands, will go on through July 14.

The two islets are located in the overlapped Exclusive Economic Zones (EEZ) respectively claimed by Japan and South Korea.

In April, Japan's intended marine survey by its Coast Guard vessels around the disputed islets nearly led to a military confrontation with South Korea. The Japanese government said the planned survey came in response to South Korea's move to propose naming the sea-floor topography of the area during an international conference.

The two countries later reached a compromise through a vice ministerial meeting in Seoul, but their EEZ negotiations held in Tokyo in mid June failed to produce any tangible results except for an agreement to hold further talks in September.

Source: Xinhua