"This action violates international norms of disarmament and nonproliferation, as well as the current international moratorium on nuclear testing. It aggravates regional tensions in and around the Korean Peninsula, and jeopardizes security both in the region and beyond," Annan said in a statement issued Monday.

The Secretary-General calls on all parties to respond to this grave challenge in a constructive manner, and calls for serious negotiations to be renewed urgently in the framework of the six-party talks.

The U.N. chief views this test as yet another reason for the international community to renew its collective effort to bring the Comprehensive Nuclear-Test-Ban Treaty into force and to make progress towards multilateral nuclear disarmament.

The Korean Central News Agency of DPRK reported Monday that Pyongyang had successfully detonated an underground nuclear test explosion. The U.N. Security Council is currently holding an emergency meeting to discuss the nuclear issue on the Korean Peninsula.