BANGKOK, Thailand - UN inspectors have verified that North Korea has shut down its nuclear reactor, the chief of the UN nuclear watchdog agency said Monday.

North Korea's spent nuclear fuel rods kept in a cooling pond are seen at the nuclear facilities in Yongbyon, North Korea, in this 1996 file photo, released from Yonhap, Feb. 7, 2003. [AP]

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

"Our inspectors are there. They verified the shutting down of the reactor yesterday," said Mohamed ElBaradei, chief of the UN 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 in Bangkok, where he was to attend an event sponsored by Thailand's Ministry of Science.

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

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

A North Korean diplomat said Sunday that his country was willing to discuss disclosing the full extent of its nuclear programs as well as disabling them as long as the US removed all sanctions against the country.

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

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

North Korea said it shut down the reactor on Saturday. It was the first on-the-ground achievement toward scaling back the country's nuclear ambitions since an international standoff began in late 2002.

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

The ministry noted that 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 toward 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 UN 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 Korea'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 six-party disarmament talks this week in Beijing along with China, Japan, Russia, South Korea and US.

Hill, a US 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.