The U.N. 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 U.S. 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," he added.
He said his information came from U.S. and International Atomic Energy Agency personnel working with the North Koreans at Yongbyon.
Asked about the North Korean developments, Secretary of State Condoleezza Rice said the U.S. wants to keep the disarmament process moving forward.
"We are expecting North Korea to live up to its obligations. And we will most certainly live up to our obligations," she said.
North Korea, which carried out an underground nuclear test blast in October 2006, later agreed with the U.S. and four other countries to disable the plant in Yongbyon, north of the capital Pyongyang. Work began in November last year.
But it then slowed the work to protest a delay in promised aid from its negotiating partners.
There was major progress in June after the North submitted its long-delayed account of its nuclear activities and destroyed its nuclear cooling tower in a show of its commitment to denuclearization.
The U.S. then announced it would take the North off the terrorism blacklist, a coveted goal of the North's cash-strapped regime. But Washington has demanded that North Korea must first agree to a plan to verify an accounting of nuclear programs it submitted in June before it can be taken off the list.
The IAEA said in a report made public on Wednesday that its monitors observed the removal and storage of fuel rods and other important equipment from North Korea's nuclear complexes, and have some material under surveillance.
More than half of the spent fuel rods at the nuclear power plant have been discharged, measured by the IAEA and moved to an adjacent spent fuel pond, the U.N. nuclear watchdog said in the report.
"These fuel rods, as well as those remaining in the reactor core, are under agency surveillance," it said.
Though McCormack played down the North Korean moves, he said Rice planned to dispatch Christopher Hill, Washington's chief North Korea nuclear envoy, and his deputy Sung Kim to Beijing on Thursday to consult with China about the situation. China, South Korea, Japan and Russia are also parties to the nuclear disaramament agreement.
South Korea's government said it was "seriously concerned" about the North's moves and was urging North Korea not to further aggravate the situation.
Japan's public broadcaster NHK and Kyodo News agency reported that North Korea started putting the facility back together Tuesday, while South Korea's Yonhap news agency reported it began Wednesday.
