South Korea plans to raise the issue of Japan's wartime sexual enslavement at the United Nations next week, government sources said Friday, a move aimed at putting pressure on Tokyo to resolve the issue with sincerity.

South Korea is expected to take the issue of Japan's refusal to recognize its wartime army's coercion of Korean women into sex slaves to a U.N. meeting to be held under the theme of advancement of women from Monday through Wednesday, sources said. Since 2011, Seoul has brought up the issue at the U.N. General Assembly.

The move comes as Japan has not budged in coping with the issue of so-called "comfort women," a source of diplomatic tension between Seoul and Tokyo.

In April, the two countries agreed to hold a monthly meeting on the issue of sex slaves, but they skipped the meeting in June due to Japan's review of its 1993 landmark statement that acknowledged its wartime sexual enslavement of Asian women for its troops during World War II.

The Kono Statement, written based on accounts from 16 Korean victims, has been a key element of the basis of relations between Seoul and Tokyo.

But in what's seen as backpedaling on the official apology, Japan said in June that the statement was the outcome of political compromise between Seoul and Tokyo, inviting strong criticism from South Korea and China.

Mindful of such criticism, Japanese Prime Minister Shinzo Abe has vowed to uphold the spirit of the statement.

But since Japan's Asahi Shimbun newspaper in August retracted its reports containing a Japanese man's accounts that Korean women were forcibly and violently dragged into sex brothels, ring-winged Japanese politicians have claimed that the 1993 statement should be revised or nullifed.

Navi Pillay, former U.N. High Commissioner for Human Rights, in August called on Tokyo to seek a "comprehensive, impartial and lasting resolution" to the sex slave issue.

Seoul and Tokyo held a fourth round of talks on Japan's sex slaves on Sept. 19, where South Korea urged Japan to come up with substantive measures as it believes discussions alone are not sufficient to resolve the issue. (Yonhap)