TOKYO (Reuters) - The U.N. nuclear watchdog has reached an “understanding” with North Korea on verification of the shutdown and sealing of the North’s Yongbyon reactor, Kyodo news agency said on Friday.

Olli Heinonen (C), nuclear safeguards director for International Atomic Energy Agency (IAEA), talks to reporters in Pyongyang June 29, 2007, after an inspection of the Yongbyon nuclear facility that North Korea has promised to mothball as part of an aid-for-disarmament deal, Kyodo news agency reported. REUTERS/Kyodo

The head of the U.N. delegation said he was satisfied with a tour of the reactor complex north of Pyongyang that the secretive state has promised to scrap under an aid-for-disarmament deal, Kyodo said.

“We have now a mutual understanding how to do the verification and monitoring of the Yongbyon facilities when they will be shut down and sealed,” Kyodo quoted International Atomic Energy Agency (IAEA) Nuclear Safeguards Director Olli Heinonen as saying.

“I think it was a very good visit, and we saw a lot of facilities,” Heinonen told reporters after concluding his talks with North Korea.

The visit to the Yongbyon reactor, about 100 km (60 miles) from the capital, is the first by IAEA officials since Pyongyang kicked out the Vienna-based agency’s inspectors in December 2002.

The communist state subsequently opted out of the nuclear Non-Proliferation Treaty, announced that it had atomic bombs and, last year, carried out its first nuclear test.

The reactor at Yongbyon was still operating, Heinonen was quoted as saying on his return to Pyongyang.

“We are satisfied,” Heinonen said, adding that the IAEA team had been able to see all of the sites it wanted to, including a plutonium reprocessing plant where weapons-grade material can be extracted from spent fuel rods.

UP TO SIX COUNTRIES

After talks later on Friday, Heinonen said the question of when the shutdown would begin was up to the six countries involved in talks on Pyongyang’s nuclear arms program.

“Now it’s up to our board of governors to make a decision. We will go back home and report the results of this discussion,” Kyodo quoted the IAEA official as saying, adding that the board would meet “maybe in one week’s time”.

The sprawling Yongbyon complex of more than 100 buildings is at the heart of North Korea’s nuclear program, which dates back to at least the 1980s.

In South Korea, the Yonhap news agency quoted an unidentified Foreign Ministry official as saying: “The IAEA could announce the date (for Yongbyon’s shutdown) as early as this week.”

A diplomat close to the IAEA had said earlier that if the team finalized terms for an inspection mission, the agency’s 35-nation board of governors would meet -- probably on July 9 -- to ratify the deal.

Kyodo said “five places” would be subject to inspections.

The disarmament deal, under which Pyongyang would receive energy aid, security guarantees and better diplomatic standing in return for scrapping its nuclear arms programs, was stalled for weeks by a dispute over some $25 million in North Korean funds frozen in a Macau bank at Washington’s behest.

Following the release of the funds, North Korea agreed this week to implement the deal it struck in February with South Korea, China, the United States, Russia and Japan.

South Korean Foreign Minister Song Min-soon, in Washington for talks with U.S. officials, has hinted at a possible early resumption of the six-way nuclear disarmament talks involving North Korea and those five countries.

“It would be effective to hold the talks at an appropriately linked time with the shutdown,” Song told South Korean reporters, Yonhap said.