The United Nations has suspended a major training program for North Korean diplomats in response to Pyongyang's recent nuclear test, an informed source here said Monday.

The U.N. planned to invite a group of North Korean diplomats to the disarmament-related program set for late this month.

But it has been indefinitely delayed as U.N. member states have shown a negative attitude toward financial support, according to the source.

In the annual training session that lasts several weeks, some North Korean diplomats are given opportunities to visit the U.N.

headquarters in New York, the U.N. Institute for Disarmament Research in Geneva or other U.N. facilities.

The U.N.'s decision is yet another sign that the North's diplomatic isolation has been deepening since its Jan. 6 nuclear test, the source said.

Earlier, the World Economic Forum withdrew its rare invitation for North Korean Foreign Minister Ri Su-yong to attend its annual Davos forum.

The U.N. Security Council is working to adopt a resolution to impose additional sanctions on the North.

Shin Dong-ik, South Korea's deputy foreign minister for multilateral and global affairs, is in New York to meet the envoys of the 15 member states of the council.

South Korea, which is not a member of the council, is seeking to make the case that the international community should take strong punitive action against Pyongyang.

South Korea's top nuclear envoy will also head to Moscow later Monday for talks with his Russian counterpart Igor Morgulov. (Yonhap)