"The meeting started at around 3pm local time," a RoK foreign ministry official told Reuters, without providing further details.

Wi Sung-lac, RoK's nuclear envoy, and Ri Yong-ho, DPRK's vice foreign minister who handles nuclear diplomacy, were meeting for unofficial talks on the sidelines of the ASEAN foreign ministers' meeting.

The RoK's Yonhap news agency said they were discussing a wide range of nuclear disarmament issues.

It quoted a RoK diplomat as saying that the RoK had conveyed its proposal for talks to DPRK on Thursday but had yet to receive a reply. The agency said "hectic diplomatic efforts" were under way to arrange a meeting between the two envoys.

The meeting marks the first high-level contact between the two Koreas since the last round of the six-way nuclear disarmament talks in 2008 and a step forward in the diplomatic effort to resume negotiations.

RoK, the United States and China, which hosts the six-way forum, have agreed on a three-stage process for envoys from Seoul, Pyongyang and Washington to meet first before the negotiations can resume.