Photo/Illutration“Hae Yang 2000,” a South Korean survey ship, enters Japanese water near the disputed Takeshima islets in the Sea of Japan on May 17. (Provided by the 8th Regional Coast Guard Headquarters)

A South Korean ocean research vessel intruded into Japan’s exclusive economic zone (EEZ) near the disputed Takeshima islets in the Sea of Japan on May 17, sparking a Foreign Ministry protest.

The ship belongs to the National Oceanographic Research Institute and had not sought permission to engage in research activities there, the Foreign Ministry said.

South Korea claims ownership of the islets, which it calls "Dokdo."

The Foreign Ministry said the crew members of the survey ship dragged a "wirelike material" in the water, suggesting that some sort of underwater survey was in progress.

Japan also lodged a complaint after a similar incident when a South Korean vessel entered Japanese waters without permission in January.

“We will confirm the facts,” said a South Korean government official in response to Tokyo's complaint.