The leaders said in a statement on Tuesday that the nuclear test and subsequent short-range missile launches constitute 'clear violations' of an international disarmament deal and UN Security Council resolutions and decisions.

The leaders also said the peaceful settlement of the North Korean nuclear issue is 'essential' to maintain regional peace and stability.

The statement was issued at the end of a two-day summit between South Korean President Lee Myung Bak and leaders of the 10-member Association of Southeast Asian Nations.

North Korea's underground nuclear test and subsequent short-range missile tests have drawn a chorus of international criticism. Further escalating tension on Monday, the North was reportedly preparing to launch another long-range missile.

South Korean President Lee Myung Bak and the Asean leaders also said during the summit that the nuclear test clearly violated a UN Security Council resolution and an international disarmament deal banning such acts.

They urged the reclusive communist regime to quickly return to stalled six-party talks involving the two Koreas, the US, China, Russia and Japan, Mr Lee's office said in a statement.

North Korea agreed in 2007 to disable its nuclear facilities in return for international energy aid and other benefits, but the negotiations have gone nowhere amid differences over how to verify its past nuclear activities. -- AP