Prime Minister Shinzo Abe has instructed Foreign Minister Fumio Kishida to visit South Korea by year-end to make an attempt to resolve the wartime "comfort women" issue, sources close to Japanese-Korean ties said Thursday.

The dispute has been a major sticking point between the two countries and had prevented Abe and South Korean President Park Geun-hye from meeting one-on-one until last month, when they met under pressure from the United States.

A diplomatic source said Kishida plans to head to South Korea on Monday, at the earliest, to discuss the issues of the ianfu (comfort women) with South Korean counterpart Yun Byung-se. Ianfu is Japan's euphemism for the women and girls rounded up to provide sex to Japanese soldiers at Imperial Japanese Army brothels before and during the war.