The U.S. diplomat handling efforts to end North Korea's nuclear ambitions has told Chinese officials that Pyongyang must admit and destroy, all its nuclear weapons programs. Joseph DeTrani is in Beijing to prepare for another round of talks to end the standoff.

Washington's top negotiator in the North Korean nuclear dispute has stressed to China any disarmament deals must include all of Pyongyang's nuclear programs.

North Korea admits to having a plutonium-based weapons program. The United States, however, says Pyongyang also has a uranium program, which the North denies.

U.S. embassy officials in Beijing say that negotiator Joseph DeTrani met with Chinese Vice Foreign Minister Wang Yi on Friday. Mr. DeTrani arrived in China Thursday to discuss plans for holding a fourth round of multilateral talks on the North's nuclear ambitions.

China has organized three rounds of talks in the past year, bringing together the United States, North and South Korea, Japan and Russia.

Robert Einhorn is an expert in North Korean disarmament issues with the Center for Strategic and International Studies in Washington. He says China is pushing both Washington and Pyongyang to come to an agreement. "I think the Chinese very much would like to influence, the course of the six-party talks," he said. "And its increased contacts and assistance to North Korea are designed to give it some influence over North Korean policies."

China is North Korea's closest ally and contributes a vast amount of aid to the impoverished neighbor. This year, Chinese officials have worked to boost the relationship with Pyongyang.

Washington insists that North Korea give up its nuclear programs, but Pyongyang says it must first have security guarantees and aid.

During talks in June, the United States laid out a plan in which a North Korea nuclear freeze would lead to ending the programs in return for some aid. Pyongyang has rejected the idea as a "sham".

In about two weeks, mid-level diplomats from the six countries involved in the nuclear dispute will gather in Beijing in preparation for a fourth round of talks. Although the talks are expected to take place by late September, no date has been set.