Top diplomats from nearly 30 Asia-Pacific countries and regional powers will meet Tuesday to discuss regional security issues such as North Korea's nuclear weapons program.

The ASEAN Regional Forum, the largest regional security gathering, will be attended by foreign ministers from the 10 members of the Association of Northeast Asian Nations and top officials from other parts of Asia, North America, Europe and Oceania.

The ARF is a rare international occasion attended by the North along with all the other countries that were involved in the six-party talks aimed at curbing Pyongyang's nuclear ambitions.

The forum consists of two sessions -- retreat and plenary -- that will kick off in the afternoon at the National Convention Center in the Laotian capital. South Korea's Foreign Minister Yun Byung-se and North Korea's Foreign Minster Ri Yong-ho are to take part in the forum.

The North's nuclear program and territorial disputes over the South China Sea are expected to be high on the agenda.

Keen attention will be placed on what Ri will say during the forum. It is scheduled to last for more than three hours.

Since his arrival here on Sunday, Ri has stayed almost mum, rarely responding to media questions. His attendance at the ARF comes amid heightened tensions caused by the North's repeated missile provocations and rumors that it might be preparing a fifth nuclear test.

On Monday, he and Chinese Foreign Minister Wang Yi held bilateral talks where they expressed hopes for better ties between the two countries. This marked the first ARF meeting between the North and China in two years.

Their traditionally close relations have been strained after North Korea's defiant military provocations despite warnings issued by Beijing and China's participation in international sanctions against Pyongyang.

The Ri-Wang talks came as Beijing's ties with South Korea have cooled following the move by Seoul and Washington to deploy a Terminal High Altitude Area Defense battery on the peninsula. China and Russia have both objected to the move, saying that it could undermine their strategic security interests.

In his talks with South Korea's Foreign Minister Yun Byung-se, Wang strongly blamed South Korea for hurting the foundation of their trust by pushing to place the missile defense system.

Meanwhile, South Korea has been working hard to reflect its concerns about the North's nuclear and missile development in the chair's statement to be issued after the forum.

The Seoul government earlier expressed worries that it might be tough this time around to get its views reflected given Laos's close ties with North Korea. Laos is this year's chair country, and ARF observers say the chairmanship is given leeway when writing the statement that will be released following the talks. (Yonhap)