South Korean President Park Geun-hye says the door is open for talks with the North on beginning the process of reunification during the upcoming U.N. General Assembly, and has urged Japan to take "courageous" action on the issue of wartime sex slaves.

However, Park said in an interview with Reuters, Pyongyang must show sincerity in seeking a constructive dialogue and "walk the talk" in taking up South Korea's offers for engagement.

Park also called for a "courageous decision" by Tokyo to improve ties between the two nations. Relations have chilled deeply over the past two years largely over the issue of Korean "comfort women," as those forced to work in Japanese military brothels during World War II are known.