"The monitors are ready to go in. Exactly when depends on when North Korea says the fuel oil has arrived and [their] inviting in the IAEA team," an agency official said.
The IAEA approval came 10 days after senior IAEA and North Korean officials agreed ground rules for verifying the atomic halt.
"The shutdown of North Korea's nuclear facilities at Yongbyon ... together with IAEA monitoring and verification, will be an important step toward achieving the common goal of a Korean Peninsula free of nuclear weapons," Gregory Schulte, US ambassador to the IAEA, told reporters.
"North Korea has only one card in hand and that is its nuclear programme
Rahy, Tehran, Iran
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Diplomats said nine inspectors would install security cameras and place seals on infrastructure in Yongbyon, including its five megawatt reactor where North Korea has produced plutonium, leading to its first test nuclear explosion last October.
Their initial mission is expected to take about two weeks and at least two monitors will stay on site while North Korea and five powers, the United States, Russia, China, Japan and South Korea, negotiate further steps towards denuclearisation.
South Korea said China may this week announce dates for fresh talks to advance the North's denuclearisation.