North Korea's testing of a nuclear device last month illustrates the need for a world ban on such tests, the head of the U.N. nuclear watchdog agency said Thursday.

Mohamed ElBaradei, head of the International Atomic Energy Agency, also called on established nuclear weapon states — such as the U.S. — to move toward nuclear disarmament.

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ElBaradei, in Tokyo for talks with Japanese officials, said at a lecture that Pyongyang's test showed the need to put tight controls on the spread of uranium enrichment and nuclear fuel reprocessing technology.

"This event also re-emphasized in my view the urgent need to establish a universal ban on nuclear testing," ElBaradei said.

North Korea carried out the test Oct. 9, triggering international anger and U.N. Security Council sanctions.

The agency chief also said a world nonproliferation system would not endure without serious steps by weapons states toward disarmament.

"There is still ... a sense of cynicism that nuclear weapons, despite what we say, are still important for deterrence, are still important for power, are still important for influence," he said.

"To change that environment, in my view, the weapon states need to lead by example," added ElBaradei, the winner of the 2005 Nobel Peace Prize.

Later Thursday, ElBaradei met with Japanese Foreign Minister Taro Aso, who explained Tokyo's stance on resuming stalled six-party talks over Pyongyang's nuclear program, ministry official Kaoru Magosaki said.

ElBaradei and Aso also discussed Iran's uranium enrichment activities and international moves aimed at pressuring Tehran to abandon its nuclear program, Magosaki said. The pair agreed it would be best if both North Korea and Iran accepted inspections by the IAEA, he said.

Iran has repeatedly refused to suspend uranium enrichment — a process that could lead to building nuclear weapons — in defiance of an Aug. 31 deadline set by the U.N. Security Council. In response, the U.S. and its European allies have been pushing for the Security Council to pass a resolution that would penalize Tehran.