China and the United States have begun talks on ending the nuclear standoff with North Korea. The move comes as Pyongyang lashed out at Seoul for taking in a record number of North Korean refugees this week.

The State Department's lead negotiator on North Korean affairs, Joseph DeTrani, began discussions with his Chinese counterparts on Thursday. Their aim is to prepare for working-level meetings focused on resolving the 21-month nuclear standoff with North Korea.

"Our special envoy Mr. DeTrani was invited to Beijing to discuss preparations for the next six-party working group session," says Adam Ereli, a spokesman for the U.S. State Department. "He plans to meet with his Chinese counterpart Ning Fukui, and he may meet other People's Republic officials as well."

While U.S. and Chinese diplomats confer, North Korea is preparing to send a top foreign ministry official to travel to New York. Pyongyang's deputy head for U.S. affairs, Ri Gun, will attend a private conference in early August. He will be the highest-ranking North Korean official to visit America in years.

A few weeks ago, North Korea's ambassador to the United Nations traveled to Washington, the first visit to the capital by a North Korean since President Bush took office. The flurry of diplomatic action may indicate some progress in stalled negotiations over North Korea's nuclear program.

The United States, China, South Korea, Japan and Russia are trying to persuade Pyongyang to give up efforts to build nuclear weapons. North Korea, however, wants security guarantees and aid before it will consider dismantling the programs.

On Thursday, tensions between North and South Korea appeared to be on the rise after Seoul took in more than 450 North Korean defectors earlier this week.

North Korean state media lashed out on Thursday, accusing Seoul of kidnapping the refugees and committing a terrorist crime.

North and South Korea had previously scheduled a cabinet level summit for early August. Following Pyongyang's statements there are concerns that North Korea may boycott those meetings.

The mass relocation was the largest single defection case from North Korea in more than half a century.