A senior colonel in the People's Liberation Army defected to the United States while visiting as part of a delegation of Chinese officers, sources reported this week. One Chinese source described it as a "grave incident" between Beijing and Washington.

The delegation visited Canada and the United States at the end of last year, one Chinese source said. Another said the group was in the United States in January when the officer disappeared.

Chinese sources could not immediately provide the officer's name. But they identified him as a member of the foreign affairs department of the army's general staff who was involved in managing China's military relations with the United States and disarmament issues.

The officer's defection was first reported in Wednesday's editions of Taiwan's United Daily News. Sources told The Washington Post about the defection earlier this week. It was confirmed today by knowledgeable U.S. sources.

A spokesman at the U.S. Embassy in Beijing also confirmed the officer was in the United States. "The Chinese government asked us in December for assistance in locating a Chinese military officer who disappeared in New York City," he said. "We located this individual, who is in good health, and notified the Chinese government."

A Chinese source with close ties to the country's intelligence services said U.S. officials arranged for the officer's defection before he visited the United States and helped him "disappear" once the delegation arrived on the East Coast.

That source added that China's intelligence community believes that U.S. officials in Beijing arranged at the same time for the man's wife to attend a party at the U.S. Embassy here. She was then given travel documents and moved to the United States.

"The Americans put her on the guest list, she went in and she never came out," the source said. "Our assumption is that she was taken to the United States."

The defection would constitute one of the most serious intelligence setbacks for China in years. It follows the August 1999 execution of two senior officers, Maj. Gen. Liu Liankun and Senior Col. Shao Zhengzhong, for allegedly spying for Taiwan.

That case rocked the People's Liberation Army, but also did enormous damage to Taiwan's ability to penetrate China's military. Liu and Zhao had worked for years in the army's armaments departments and were familiar with China's military capabilities regarding Taiwan, an economic powerhouse of 23 million people that China claims to be part of its territory.

The defection also follows the sentencing late last year of the chief of China's military intelligence bureau, Maj. Gen. Ji Shengde, to 15 years for corruption and smuggling. Chinese sources said Ji's removal and subsequent investigations of other military intelligence officials have significantly hampered China's ability to collect military intelligence.

The source with close ties to China's state security bureau said that when they discovered their colleague's disappearance, the military delegation informed China's Defense Ministry and the Chinese Embassy in the United States, which demanded the U.S. government find the officer and hand him over. When the Americans failed, the Chinese delegation returned home immediately, the source said.

Subsequently, the Central Military Commission, China's top military organization, which is chaired by President Jiang Zemin, held a meeting on the issue. The PLA has since undertaken investigations of hundreds of officers who deal with foreigners to avoid a repeat incident, Chinese sources said.