North Korea announced on Friday its intention to restart its Yongbyon nuclear reactor as disarmament talks stalled.

The controversial reactor's restart was under preparation, the official South Korean Yonhap news agency quoted a North Korean official as saying.

Foreign ministry official Hyon Hak-Bong said during energy aid talks in the border truce village Panmunjom that Pyongyang was making "thorough preparations" to restore nuclear facilities.

"You may say we have already started work to restore them," he said, adding that the communist state would soon announce when the reactor would be restarted.

North Korea, annoyed as the United States did not - as agreed in disarmament talks earlier this year - remove the communist state from its terrorism blacklist, stopped disabling the plutonium-producing reactor in late August and threatened to restart its nuclear weapons programme.

Hyon accused the US of not keeping its part of a deal struck in six-nation disarmament talks in November and demanded his country's immediate removal from a US list of countries sponsoring terrorism.

In talks with the United States, China, Russia, Japan and South Korea, the North agreed to disable its nuclear weapons programme in exchange for energy aid and an easing of sanctions.

The United States made Pyongyang's agreement to verification of its disablement a prerequisite for ending some of its sanctions, a demand which Hyon rejected as "unacceptable."

South Korea said in early September that North Korea had started to rebuild its previously disabled nuclear facilities.

Uncertainty over the health of North Korean leader Kim Jong Il, who has not been seen in public for months, adds to the stalemate.