South Korea President Lee Myung-Bak urged Tokyo on Saturday to compensate Korean wartime sex slaves, warning the issue would otherwise remain a \"burden\" forever, after he arrived in Japan for a summit.Lee arrived at a government guesthouse in the the ancient city of Kyoto after flying into Osaka International Airport for a two-day visit. The summit, meant to discuss trade, North Korea and other bilateral issues, is overshadowed by the issue of \"comfort women\", a euphemism used to describe women forced into sexual slavery before and during World War II. \"Unless we resolve this issue, Japan will have the burden of being unable to resolve (the) outstanding issue... forever,\" South Korea\'s Yonhap news agency quoted Lee as saying.He warned that time was running out and the matter should be considered urgently. \"Now there are not many left. This year alone, 16 of them passed away. In the not-distant future, all of them will pass away,\" he said, referring to the women. Resolving this issue while they are alive will be of big help for the two countries to move forward toward the future.\" Lee is expected to discuss the issue with Japanese Prime Minister Yoshihiko Noda on Sunday, as the two leaders hold formal talks. \"The (South Korean) government has been raising the issue of comfort women with Japan through various diplomatic channels,\" a senior South Korean foreign ministry official noted earlier this week. \"There is no reason for us not to raise it at the upcoming summit. We are going to discuss various issues, including the issue of comfort women,\" the official told reporters on condition of anonymity. Elderly South Korean women forced into Japan\'s wartime military brothels held their 1,000th weekly protest in Seoul Wednesday, demanding an apology and compensation. Demonstrators set up a statue of a teenage Korean girl in traditional costume to represent sex slaves outside the Japanese embassy despite protests from Tokyo. The issue of comfort women came to widespread notice in the early 1990s after some victims found the courage to go public. Japan has apologised for the military\'s crimes against the women but rejected rejected South Korea\'s proposal of bilateral talks about the women\'s demands. Tokyo, which ruled Korea from 1910-45, says all claims for colonial-era suffering were settled in a 1965 compensation agreement with Seoul.