U.N. nuclear agency inspectors will return Saturday to North Korea to monitor the shutdown of its sole operating nuclear reactor, the agency head said Wednesday, a sign that Pyongyang is complying with its disarmament pledge.

It would be the first time in nearly five years for North Korea to receive inspections from the International Atomic Energy Agency since the hardline communist regime expelled IAEA monitors shortly after the latest nuclear crisis erupted in late 2002.

IAEA chief Mohamed ElBaradei said upon his arrival in Seoul that the monitors were expected to travel Saturday and arrive in Pyongyang the same day. He said it was not known if the reactor could be shut down before the inspectors arrive.

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"We will verify that they will shut it. Whether they shut it before or not, that is immaterial," ElBaradei told reporters.

North Korea has said it would be willing to shut down its Yongbyon reactor after receiving an initial shipment of oil under a February deal where the Pyongyang pledged to start dismantling its nuclear weapons program.

South Korea, who is shipping the oil, said the shipment is expected to arrive Saturday in the North.

ElBaradei came to Seoul to attend an international atomic technology conference scheduled for Thursday, but his visit also includes meetings with South Korean President Roh Moo-hyun and Foreign Minister Song Min-soon.

During his meeting with Roh, Elbaradei said much time has been lost in international efforts to end the North's nuclear programs and the disarmament process should speed up.

He expressed hope that the North would ultimately rejoin the Nuclear Nonproliferation Treaty and dismantle its nuclear weapons, but also warned that it would be a lengthy and difficult process.

"We have to be patient," he said.

Elbaradei, who visited the North earlier this year, has no known plans to travel to the communist nation.

Earlier Wednesday, South Korean Foreign Minister Song also said IAEA monitors were expected to arrive in the North over this coming weekend, adding that Pyongyang's shutdown of Yongbyon is expected to come in a similar timeframe.

If the North shuts down the reactor, it would be the first move it has made to scale back its atomic weapons development since the nuclear standoff began in late 2002.

Since then, North Korea is believed to have produced enough plutonium from its sole operating reactor at Yongbyon to make as many as a dozen bombs or more, and conducted its first-ever nuclear weapons test explosion in October.

The halting negotiations aimed at getting the North to stop its nuclear weapons production have gained new life in the wake of the test after the U.S. reversed its previous hard-line stance on the North and showed willingness to meet Pyongyang's demands — including its main condition of freeing money frozen in a Macau bank.

The IAEA's board of directors, meeting Monday in Vienna, approved the coming weekend's mission, following a visit there by the agency's deputy director general late last month to discuss details of verifying the shutdown.

Song said Wednesday that the chief delegates from countries involved in international talks over the North's nuclear program — China, Japan, Russia, the United States and the two Koreas — were expected to meet next week in Beijing even though the Chinese hosts have not yet formally announced the talks.

Washington has also said its chief nuclear envoy, Assistant Secretary of State Christopher Hill, would depart for the region over the weekend and was expected to participate in the six-nation talks around July 18. The negotiations were last held in March.

Next week's meetings are expected to discuss details of the North's pledge to declare and disable its nuclear programs and facilities in exchange for an additional energy aid and political concessions from other countries, Song said.

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