Korea's foreign ministry denounced Japan on Thursday for repeating its territorial claim to Seoul's easternmost islets of Dokdo.

In a statement issued in the name of its spokesman, the ministry demanded Japan stop an annual local event to promote its territorial right to the islets.

"The Japanese government should immediately stop its unjustified claim to Dokdo, our inherent territory from a historic and geographical perspective, as well as in the eyes of international law," spokesman Noh Kyu-duk read from the statement during a regular press briefing.

"It should show the attitude of a responsible country by looking squarely at history in a humble way."

Tokyo sent a vice minister-level official as a government representative to the so-called Takeshima Day event held earlier in the day. Takashima is the Japanese name for Dokdo.

This marked the sixth year in a row that such a high-ranking official has joined the controversial event.

In 2005, Japan's Shimane Prefecture, which claims administrative sovereignty over the islets, designated Feb. 22 as Takeshima Day.

Dokdo, which lies closer to Korea than Japan in the East Sea, has long been a recurring source of tension between the neighbors.

Korea has kept a small police detachment on Dokdo since its liberation from Japan in 1945 and has made clear that Tokyo's claims are utterly groundless.

This comes after Japan repeated its claim to Dokdo by unveiling a draft of textbook guidelines for high school students last week in which it ordered it should be taught that the islets are part of Japan's territory.

The latest controversy is expected to add to diplomatic challenges facing the two countries, which have seen their ties chilled over a 2015 deal they reached to resolve the longrunning feud over Japan's wartime sexual slavery of Korean women.

In January, the Seoul government said that the comfort women issue has not been resolved by the deal and emphasized that "relevant" countries should help the victims recover their dignity and heal their wounds from the harrowing wartime experience.

Japan has protested against changing the government-to-government deal, saying any attempt to modify or scrap it could negatively affect bilateral relations between the neighbors.(Yonhap)