Diplomats attending a Southeast Asian security forum in Malaysia say North Korea has threatened to quit the annual gathering if the organization criticizes Pyongyang over its missile tests.

North Korean Foreign Minister Paek Nam Sun, center, is surrounded by aides, at ASEAN meeting

Officials at the talks say North Korean Foreign Minister Paek Nam Sun made the threat Friday during the forum's opening session in Kuala Lumpur.

The forum brings together foreign ministers from the Association of Southeast Asian Nations and other world powers.

Delegates say some ministers at the closed door meeting criticized North Korea for test-firing seven missiles earlier this month.

They say North Korea's Paek defended the missile tests as necessary for self-defense.

After the opening session, U.S. Secretary of State Condoleezza Rice convened an informal meeting with nine other countries to discuss reviving stalled talks on North Korea's nuclear program.

North Korea refused to take part in the meeting, saying Washington must first end financial sanctions against Pyongyang.

The informal meeting included the five nations that have negotiated in six-party talks with North Korea in the past, the U.S., South Korea, China, Japan, Russia, plus five other countries: Malaysia, Indonesia, Canada, Australia and New Zealand.

U.S. Assistant Secretary of State Christopher Hill says North Korea is isolating itself by rejecting requests to join informal talks at the forum.

Washington has imposed financial sanctions on North Korean-linked companies suspected of money laundering and counterfeiting U.S. dollars.

Some information for this report was provided by AFP, AP and Reuters.