The chief U.N. nuclear inspector headed to North Korea on Tuesday for talks on how to implement a landmark nuclear disarmament agreement after playing down expectations that his trip heralded the communist country's rapid disarmament.

Mohamed ElBaradei, head of the Vienna-based International Atomic Energy Agency, stopped in Beijing on his way to Pyongyang for discussions on how to implement the agreement reached at six-nation talks last month.

He cautioned Monday that efforts would be "a very incremental process. There's a lot of confidence that needs to be built."

• Monitor the nuclear showdown on the Korean Peninsula in FOXNews.com's North Korea Center.

Under the Feb. 13 agreement, the North is to ultimately give up its nuclear arsenal in exchange for economic aid and political concessions.

Meanwhile, former South Korean President Kim Dae-jung urged North Korea not to miss the opportunity to get aid and other concessions for ending its nuclear weapons program.

Kim said if the North goes back on its promises that it could face strong collective sanctions from the U.S. and its four regional partners — South Korea, China, Russia and Japan.

"North Korea also has a reason to seize the opportunity to achieve success in the six-party talks," Kim said in remarks prepared for a meeting of international journalists in Seoul. He said "North Korea's survival could be threatened" if it faced tough sanctions.

Kim, who won the Nobel Peace Prize for his engagement policy toward the North, also asked the U.S. to give North Korea what it wants and embrace the isolated country as part of international society.

The U.S. has agreed to resolve a dispute over its financial restrictions on a Macau bank that was accused of complicity in counterfeiting $100 bills and money laundering by North Korea. The U.S. move led Macau authorities to freeze about $24 million in North Korean assets.

Kim's comments come as officials from the U.S. and the North prepared to meet their counterparts from South Korea, China, Russia and Japan this week in Beijing to discuss denuclearization, economic and energy cooperation, as well as peace and security in Northeast Asia.

A working group session on economic and energy cooperation will be held at the South Korean Embassy in Beijing on Thursday, the South's Foreign Ministry said Tuesday.

U.S. Assistant Secretary of State Christopher Hill, the main American nuclear envoy, was scheduled to arrive Wednesday in Beijing for the working groups and will stay at least a week, said Susan Stevenson, a U.S. Embassy spokeswoman in Beijing.

Hill is likely to meet Elbaradei, who is expected to return Wednesday to Beijing, though no official meeting has been set, according to the embassy.

The working group sessions will be followed by a full session of the six-nation North Korea nuclear talks next week.

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