SEOUL (AFP) - South Korean President Park Geun Hye on Sunday repeated a call for Japanese leaders to apologise to former wartime sex slaves, warning that "time is running out" for Tokyo. Mainstream historians say up to 200,000 women, mainly from Korea but also from China, Indonesia and other Asian nations, were forced into sexual slavery for Japanese troops during the World War II. The issue - a key sticking point in ties between the two neighbours - further strained relations in recent months amid an increasingly aggressive campaign in Japan to claim these "comfort women" were common prostitutes. Park has urged Japanese leaders to offer an apology, and on Sunday repeated the call for Tokyo to use "all means" to resolve the issue as the number of survivors rapidly dwindles.