BEIJING - A second team of UN nuclear experts arrived in North Korea on Saturday to monitor the shutdown and sealing of the country's sole plutonium-producing reactor.

The six experts from the International Atomic Energy Agency will replace an initial team that went to North Korea on July 12 to supervise the shutdown of the Yongbyon reactor, the key component of the North's nuclear program.

The IAEA confirmed last week that North Korea had shut down its sole functioning reactor at Yongbyon -- the first tangible progress after years of negotiations between the communist regime and five other countries.

"I am leading the verification mission to continue activities, monitoring and verification activities," Ryszard Zarucki told broadcaster APTN on his arrival at the Pyongyang airport, adding that he expected to stay about two weeks in North Korea.

Zarucki would not say if the second team's role was any different to that of the first.

"At this stage it is difficult to specify," he said.

Officials said the team would put agency seals on parts of the complex that have been closed and supervise the installation of surveillance cameras, whose recordings will be regularly downloaded and analyzed.

IAEA inspectors also are working to verify the status of two unfinished reactors, a spent fuel reprocessing facility and a fuel fabrication plant.

The North exploded a test nuclear weapon in October, but four months later agreed to scrap its nuclear program in exchange for economic and political concessions in a deal with the U.S., Russia, China, Japan and South Korea.

It will eventually receive the equivalent of a total of 1 million tons for disabling its nuclear facilities under a February agreement with the five countries.

North Korea has begun receiving 50,000 tons of oil from South Korea as a reward for shutting down Yongbyon, which is located 96 kilometres north of Pyongyang.

The shutdown is the first step North Korea has taken to scale back its nuclear ambitions since the crisis began in late 2002, when a 1994 disarmament deal fell apart and the North reactivated its reactor to produce plutonium for bombs.