BEIJING - North Korea's top nuclear envoy arrived Tuesday in Beijing for another round of talks on disarming Pyongyang's nuclear program, a day after the UN confirmed the country had shut down its sole functioning nuclear reactor.

The talks will now focus on having the country declare and dismantle remaining nuclear programs and how to permanently disable its reactor at Yongbyon.

Kim Kye Gwan did not say anything at the Beijing airport, but told broadcaster APTN on leaving Pyongyang that closing the reactor meant the process was moving into a second phase.

"There should be discussion on how to define the targets of the second phase, the obligations for each party, and also the sequence of the actions."

North Korea pledged in an international accord in February to shut the reactor at Yongbyon and dismantle its nuclear programs in return for 1 million tons of oil and political concessions. However, it stalled for several months because of a separate, now-resolved dispute with the US over frozen bank funds.

Mohamed ElBaradei, chief of the International Atomic Energy Agency, announced Monday that IAEA inspectors had verified that the reactor had been shut down, calling it a "good step in the right direction."

"It's a complicated process," ElBaradei said during a trip to Bangkok, Thailand. "Ultimately we will have to go and make sure the nuclear weapons arsenal of (North Korea) are dismantled. It is a very positive step we are taking this week. But we have a long ways to go."

Six-party talks on North Korea's nuclear program, which include host China, the US, Japan, South Korea and Russia, start Wednesday, but Kim said he expected to meet chief US, nuclear envoy Christopher Hill on Tuesday.

"I think I will meet Hill today," he said.

The shutdown over the weekend, confirmed by a 10-member team of IAEA inspectors who arrived in North Korea on Saturday, was the first on-the-ground achievement toward scaling back Pyongyang's nuclear ambitions since the international standoff began in late 2002.

On Monday, South Korea sent the second of two initial shipments of what eventually will be 50,000 tons of oil to reward North Korea specifically for the reactor shutdown.

Pyongyang has said that further progress under the disarmament accord would depend on if the United States and Japan changed what it called hostile policies toward North Korea.

Hill, a US assistant secretary of state, has said the negotiations would focus on a timeframe for how disarmament would proceed.

There are also plans for the foreign ministers of the six countries to meet, and US State Department spokesman Sean McCormack said such a meeting is "a likely event," with scheduling discussions to take place in Beijing.

He told reporters in Washington that the next stages, where the North is to declare all its nuclear programs and disable its reactor, are going to be hard, but that the US wants to see things move ahead "with some rapidity."

When asked about removing North Korea from a list of terrorism-sponsoring states, McCormack said that it would be important for North Korea to continue to work with Japan on an abductions issue.

Japan has opted out of the aid provision part of the February deal, citing a lack of progress by North Korea in resolving the abductions of its citizens by Pyongyang during the 1970s and 1980s.

Chinese Foreign Ministry spokesman Liu Jianchao was quoted by Xinhua News Agency as welcoming the shutdown of the Yongbyon reactor, saying all countries should "earnestly carry out their commitments."