The leaders of Japan and South Korea are not expected to hold talks on the sidelines of upcoming regional conferences that both plan to attend, in the latest sign of souring bilateral ties, sources have said.

Relations between the two neighbors appear to be rapidly deteriorating following a South Korean top court ruling last week ordering a Japanese company to pay compensation for wartime labor during Japan's 1910-1945 colonial rule of the Korean Peninsula.

The sources said Tuesday that Prime Minister Shinzo Abe and South Korean President Moon Jae-in are both expected to attend a meeting involving partners of the Association of Southeast Asian Nations in Singapore as well as the Asia-Pacific Economic Cooperation forum summit in Papua New Guinea later this month.