South Korea will hold bilateral talks with Japan and the United States on the sidelines of an annual ASEAN event to discuss North Korea's nuclear ambitions and other issues of mutual concern, informed sources said Sunday.

Top diplomats from regional powers and Asia-Pacific countries kicked off their three-day gathering in the Laotian capital of Vientiane, where they will hold a series of meetings led by the Association of Southeast Asian Nations.

South Korea's Foreign Minister Yun Byung-se plans to meet with his Japanese counterpart Fumio Kishida on Monday, followed by talks with U.S. Secretary of State John Kerry later in the day, according to the sources.

High on the agenda is their joint approach to handling North Korea's evolving nuclear program. Since 2006, the reclusive country has carried out four nuclear tests despite warnings by the international community.

Tensions on the Korean Peninsula remain high following the North's fourth nuclear test and long-range missile launch earlier this year. Some are raising worries that Pyongyang might be preparing a fifth nuclear test.

The talks with Seoul's allies will be held ahead of the ASEAN Regional Forum, the region's largest security meeting, which will be joined by all member countries of the six-party talks.

The six-party talks set up to resolve the North's nuke issue were last held in late 2008. The participating countries are the two Koreas, the United States, China, Japan and Russia.

Another major bilateral meeting that Yun is to hold is with his Myanmar counterpart and the pro-democratic icon Aung San Suu Kyi. The meeting is scheduled for Sunday, according to the sources.

Whether to hold talks with Chinese Foreign Minister Wang Yi has not been determined. Both are still working on tuning their schedules for a meeting, the sources said. (Yonhap)