South Korea said that North Korea had begun restoring its nuclear facilities. But the US played it down, saying the country apparently only moved some equipment out of storage.

The North said last week it had stopped dismantling its nuclear reactor on August 14 because Washington had not held up its end of their disarmament deal a promise to remove North Korea from the US list of state sponsors of terrorism. At the same time, the North threatened to restore the nuclear facility.

The UN nuclear watchdog agency said in a new report that North Korea had already removed "essential" equipment from its nuclear facilities by the time it decided to stop disabling them last month, suggesting it would take some time to restore its main reactor to an operational state.

South Korean and US officials have said that it would take at least a year for the North to restart the facilities after they are completely disabled.

The South Koreans did not give any specifics about what exactly the Koreans were doing to restore the Yongbyon plutonium-producing facility or when they started the work.

But in Washington, the State Department said the North had not begun reconstructing the facility.

"Our understanding is that the North Koreans are moving some equipment around that they had previously put into storage," spokesman Sean McCormack said.

"Based on what we know from the reports on the ground, you don't have an effort to reconstruct, reintegrate this equipment back into the facility," McCormack added.