U.N. inspectors have verified that North Korea has shut down its sole functioning nuclear reactor, the chief of the watchdog agency said Monday, confirming Pyongyang's first step to halt production of atomic weapons in nearly five years.

"Our inspectors are there. They verified the shutting down of the reactor yesterday," said Mohamed ElBaradei, chief of the International Atomic Energy Agency.

"The process has been going quite well and we have had good cooperation from North Korea. It's a good step in the right direction," ElBaradei said, speaking in Bangkok ahead of an event sponsored by Thailand's Ministry of Science.

Earlier Monday, South Korea sent more oil to North Korea to reward its compliance with an international disarmament agreement.

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Unification Minister Lee Jae-joung said a second shipment of oil departed Monday for the North on a South Korean ship. A first shipment that arrived Saturday — prompting the North to follow through on its pledge to shut the reactor — has been completely offloaded, Lee said at a meeting with U.S. nuclear envoy Christopher Hill.

The two shipments are part of 50,000 tons of oil that the North will receive for the reactor shutdown. Under a February agreement at international arms talks, Pyongyang will receive a total equivalent of 1 million tons of oil for dismantling its nuclear programs.

The North had said that it shut down the reactor, which generates plutonium for atomic bombs, on Saturday — the first on-the-ground achievement toward scaling back Pyongyang's nuclear ambitions since the international standoff began in late 2002.

A 10-member team of IAEA inspectors arrived Saturday in North Korea to confirm the shutdown at Yongbyon.

The North's Foreign Ministry said Sunday that further progress on disarmament would depend "on what practical measures the U.S. and Japan, in particular, will take to roll back their hostile policies toward" North Korea.

The ministry noted North Korea acted to shut down its nuclear reactor even before receiving all 50,000 tons of oil, adding that was "a manifestation of its good faith towards the agreement," according to a statement carried by the official Korean Central News Agency.

Still, North Korea emphasized Sunday that it did not view the oil as aid and that the U.N. inspectors' activities were restricted in scope.

"The provision of substitute energy including heavy oil is by no means 'aid' in the form of charity but compensation for the (North's) suspension of its nuclear facilities and the activities of the IAEA in (Yongbyon) are not 'inspection' but limited to verification and monitoring," the ministry said.

North Korea is set to participate in a renewed session of arms talks this week in Beijing, along with China, Japan, Russia, South Korea and the U.S.

Hill, a U.S. assistant secretary of state, has said the negotiations would focus on a "work plan and a timeframe" for how disarmament would proceed, adding he planned to meet his North Korean counterpart Tuesday ahead of the formal start of talks.

A North Korean diplomat said Pyongyang was willing to discuss listing its nuclear programs as well as disabling them as long as the U.S. removed all sanctions against the communist nation.

Hill said Monday during his meeting with Lee that Washington moving to remove the North's pariah status would depend on Pyongyang continuing to comply with its disarmament promises.

"With complete denuclearization, everything is going to be possible," Hill said.

Hill has said he believes the disablement of the North's nuclear facilities could be completed by the end of the year.

Complete coverage is available in FOXNews.com's North Korea Center.