The aid-for-disarmament deal - agreed last year by the two Koreas, China, the United Sates, Japan and Russia - hit a snag on Tuesday when Pyongyang said it had stopped disabling its nuclear plants.

It also threatened to resurrect its Yongbyon nuclear facility because the United States had failed to remove it from a terrorism blacklist.

The South, leading a working group commissioned by the six-party deal to provide energy aid to the North, has said it will continue the assistance for the time being despite the deadlock.

But the North remains 'lukewarm' in responding to the South's offers to resume talks on the energy aid, an unnamed source told Yonhap news agency.

'Offers were made to North Korea several times this month to discuss the resuming of the economic and energy aid working group meeting... but there was no response,' the source told Yonhap.

North Korea, which tested an atomic bomb on Oct 2006, has since 2003 been taking part in the six-party talks aimed at dismantling its nuclear arms programme in return for aid and diplomatic and security guarantees.

It has shut down the Yongbyon reactor, which produces weapons-grade plutonium, and has disabled about 80 percent of the main nuclear complex.

Seoul officials say the North has so far received about half of the one million tonnes of fuel oil or equivalent assistance promised in return for disablement.

The disarmament process has been deadlocked because of a dispute over verifying the North's nuclear declaration in June.

A Seoul official recently told AFP the communist state has refused US demands that it agree to sampling work Washington says is crucial to verifying the amount of plutonium it has produced.

Some media reports say the North puts its plutonium production over the years at around 37-40 kilos in the declaration.

US intelligence estimates it has produced 40-50 kilos.

The North claims it should be removed from the blacklist first as part of an action-for-action plan under the accord. -- AFP