Hyun's comments, which did not indicate when operations would resume, came as officials from the two Koreas met at the border truce village of Panmunjom to discuss further deliveries of energy aid.

As part of the six-party nuclear deal, North Korea was promised one million tonnes of heavy fuel oil or equivalent energy aid in return for disabling its nuclear reactor.

Work to disable Yongbyon began last November and in June the main cooling tower at the plant was demolished in what was seen as gesture of the North's commitment to the disarmament process.

The Yongbyon plant has been the centre of North Korea's nuclear programme [AFP]
In the same month North Korean officials handed the US a list of its nuclear programmes and facilities in return for what it says was a promise that Washington would start the process of removing North Korea from the US terrorism blacklist.

Washington however has refused to begin that process until the North agrees to an international plan to verify the nuclear declaration.

As a result North Korea announced in mid-August that it was calling a halt to disablement work at Yongbyon.

Speedy return

On Thursday the London-based International Institute for Strategic Studies (IISS), in its annual global security review, said that North Korean had the capability to put its nuclear programme back on track within a year.

"Diplomatic efforts to stem the nuclear proliferation challenges posed by Iran and North Korea are both deadlocked," John Chipman, the IISS chief, said.

"It will take North Korea less than one year to undo the steps that up until August it was taking to disable its declared nuclear facilities."

In its Strategic Survey 2008, the IISS said coaxing North Korea to abandon its nuclear programmes has often seemed like "trying to roll a rock up a steep mountain".

The uncertainty over the health of Kim Jong-Il, the North Korean leader, could also prolong its stalemate with the US, said the report.

"[T]here will be persistent concern in Washington not only about the uncertainty of North Korea giving up all of its plutonium, but also about security challenges posed by Pyongyang's ballistic missile programme, chemical weapons stocks and forward-deployed conventional forces, as well as about human rights," it added.