South Korean President Lee Myung-bak pressed Japan to take sincere steps to resolve long-running grievances over Tokyo's wartime sexual enslavement of Korean women, saying the act was a violation of "universal human rights and historic justice."

Lee made the remarks during a Liberation Day address marking Korea's independence from Japan's 1910-45 colonial rule, as tensions between the two countries have been running high after Lee's surprise visit last week to South Korea's easternmost islets of Dokdo, which Tokyo claims as its own.

Historians say that tens of thousands of Asian women, mostly Koreans, were forced to work at front-line brothels for Japanese soldiers during World War II. Victims of sexual slavery have been euphemistically called "comfort women."

"Japan is a close neighbor, a friend that shares basic values and an important partner that we should work with to open the future. However, we have to point out that chain links tangled in the history of Korea-Japan relations are hampering the common march toward a better tomorrow in the Northeast Asian region, as well as bilateral ties," Lee said.

"Particularly, the issue involving the mobilization of 'comfort women' by the imperial Japanese military goes beyond relations between Korea and Japan," he said. "It was a breach of women's rights committed during wartime as well as a violation of universal human rights and historic justice. We urge the Japanese Government to take responsible measures in this regard."

Lee has repeatedly stressed that the comfort women issue is becoming increasingly urgent as most victims are elderly, well over 80 years old, and may die before they receive compensation or an apology from Japan. Currently, there are only 60 victims alive.

Tokyo has been ignoring Seoul's demand for official talks on compensating the aging Korean women. Seoul has been making the demand since its Constitutional Court ruled last year that it is unconstitutional for the Seoul government to make no specific efforts to settle the matter with Tokyo.

Japan maintains that all issues regarding its colonial rule of the Korean Peninsula, including the comfort women, were settled in a 1965 package compensation deal under which the two countries normalized their relations.

Lee's trip to Dokdo, which was made Friday, has sharply raised tensions between Seoul and Tokyo. It was the first time that a South Korean president has ever visited the islets lying in the East Sea around halfway between the Korean Peninsula and Japan.

Lee has said he decided to make the trip to show through action that Japan needs to sincerely atone for its past wrongdoing, and that lack of progress in efforts to resolve colonial-era issues has kept South Korea from fully opening its heart to Japan and moving relations between the two countries forward.

On Tuesday, Lee said Japan's emperor should sincerely apologize for the country's colonial rule if he wants to visit South Korea, and that he "does not need to come" if he is going to offer an insincere apology couched in vague language, recalling the hard-to-understand, ancient wording Emperor Akihito used in his 1990 apology.

Tokyo has long laid claims to Dokdo in school textbooks, government reports and other ways.

South Korea has rejected the claims to Dokdo as amounting to denying Korea's rights because the country regained independence from colonial rule and reclaimed sovereignty over its territory, including Dokdo and many other islands around the Korean Peninsula.

Koreans also view the claims as a sign Japan has not fully repented for its imperialist past.

South Korea has kept a small police detachment on Dokdo since 1954.

Lee said South Korea will continue to make preparations for unification with North Korea.

"The ultimate consummation of our liberation consists in national unification. National reunification will be the springboard of a truly greater Republic of Korea," he said, referring to South Korea's official name.

Lee urged Pyongyang to give up its nuclear programs, embrace reform and open up to the outside world, saying the South is prepared to help the impoverished nation. Lee also said the South is open to dialogue with the communist nation.

"Pyongyang has also come to a situation where it has to look straight at reality and consider a transformation," he said. "We will carefully watch for the possible changes." (Yonhap News)