SEOUL, Feb. 7 (Xinhua) -- South Korea on Friday urged Japan to immediately respond to its long-lasting proposal for bilateral consultations on the issue of the so-called comfort women, those forced to serve as sex slaves at the Japanese military brothel during World War II.

Foreign Ministry spokesman Cho Tai-young told a routine press briefing that the South Korean government called for bilateral consultations with Japan a long while ago about the comfort women issue, urging Japan to make an immediate response to the call.

Over 200,000 young women, many of them South Koreans, were coerced into sex slavery during Japan's colonial rule of Asia. Among 237 South Korean women who identified themselves as former sex slaves, only 56 are alive.

Foreign Minister Yun Byung-se visited centers accommodating the former South Korean sex slaves ahead of the Lunar New Year holiday, the first visit as the country's foreign minister, in what appears to be a protest against the Japanese government, headed by Shinzo Abe, which has refused to apologize for its past atrocities.

New head of Japan's public broadcaster NHK infuriated South Korea and other Asian neighbors last month, saying that the Japanese Imperial Army's "comfort women" brothel system was common worldwide during war time.

Spokesman Cho said that there is little time left for Japan to make an official apology to the comfort women due to their old age, describing the recent remarks by Japanese politicians and the NHK chief as "deplorable".