SEOUL, South Korea (AP) - A top Chinese official called Thursday for efforts to quickly resume stalled talks on ending North Korea's nuclear programs, while Washington said any future disarmament deal will have to address Pyongyang's uranium enrichment program.

Chinese Vice President Xi Jinping, a rising star in the country's leadership, also said his country wants to work closely with South Korea to advance the denuclearization process on the Korean peninsula. Xi made the comments during his talks with South Korean President Lee Myung-bak in Seoul, according to Lee's office.

Xi is seen as the leading contender to eventually succeed President Hu Jintao - widely believed to be planning to step down in 2012.

In a separate meeting, Kim Hyong-o, South Korea's parliamentary speaker, asked Xi for Beijing to play a more active role to get North Korea to abandon its nuclear programs and rejoin the disarmament talks that also involve China, South Korea, Russia and Japan and the U.S.

China is widely seen as the country with the most clout with Pyongyang as it is North Korea's biggest benefactor and longtime communist ally. Its influence is seen as key to getting the North back to the negotiating table.

The remarks came as Stephen Bosworth, President Barack Obama's envoy on North Korea, said Pyongyang's uranium program will "clearly be on the agenda" when nuclear talks resume.

"They put it there," he said of the North, by publicly announcing it had finished the first experimental phase of such a program. Bosworth spoke to reporters Wednesday at the State Department after returning home from the Obama administration's first high-level talks with North Korea.

After years of denial, North Korea said in September that it was in the final stages of enriching uranium, a process that could give it a second way to make nuclear bombs in addition to its known plutonium-based program.

The disarmament talks had yielded pacts promising North Korea much-needed aid and other concessions in return for step-by-step disarmament. However, Pyongyang walked away from the talks this year in anger over U.N. Security Council condemnation of a rocket launch widely seen as a test of its long-range missile technology.

Bosworth also said the North lobbied to have sanctions eased that were put in place in June by the U.N. in repines to the regime's second underground nuclear test. Bosworth said that wouldn't happen until North Korea came back to nuclear negotiations and made significant progress on getting rid of its atomic weapons.

Both Washington and Pyongyang agreed on the need to resume the stalled talks but the North did not make a firm commitment on when it would rejoin the negotiations. Bosworth said Wednesday that he did not know when those talks might begin.

Separately, a U.S. business delegation held "an exhaustive discussion" with North Korean officials on creating an environment for investment, the North's official Korean Central News Agency reported Thursday, without elaborating.

During its four-day trip that ended Thursday, the delegation representing Business Executives for National Security also met Kim Yong Nam, the country's No. 2 leader, and other top officials while visiting a university and factories in Pyongyang, KCNA said.

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Associated Press writers Foster Klug in Washington and Scott McDonald in Beijing contributed to this report.