The Chinese government has agreed to release a severely injured U.S. citizen detained in Qinghai province, and the man was to be evacuated to Hong Kong today, an official source said.

Daja Meston, 29, a Tibetan advocate from Newton, Mass., came to China in late July to conduct an independent inspection of the site of a proposed World Bank resettlement program. He was detained Aug. 15 in remote Dulan county, along with an Australian and a Chinese citizen, and accused of engaging in an "illegal investigation."

After being interrogated for more than three days by state security agents, Meston jumped from a third-story window. He suffered a broken back and was hospitalized with severe internal injuries.

"He's due to fly out on a medevac to Hong Kong. Once there, he will be stabilized for one to three days, then flown on a stretcher on a commercial airline back to Boston," the source said.

An emergency flight by an American medical evacuation company based in Beijing, AEA International, arrived in Xining, the capital of Qinghai, at 11:20 a.m. local time today, an airport official said.

Meston's wife, Phuntsok Meston, arrived in Qinghai on Wednesday to see her husband. Chinese security agents have kept a tight watch on the couple in the hospital and have repeatedly videotaped the Mestons, an official source said. Phuntsok Meston told family members in a tearful telephone call on Wednesday that her husband would be sent to Hong Kong today, but was in "bad condition," her sister said.

Although Daja Meston's release appeared imminent, it remained unclear how the Chinese would proceed with their case against him, and whether he would have to sign a confession or other documents. The Australian who was detained with Meston was released Saturday after confessing to a host of Chinese charges.

On Wednesday, State Department spokesman James Foley said Chinese officials told their U.S. counterparts that "the investigation . . . will be wrapped up by the time he's able medically to travel."

"Qinghai provincial officials indicated to the embassy that Mr. Meston could be medevaced and that they will resolve his legal situation prior to his departure," Foley said.

After spending a few days in Hong Kong, Meston is to be taken back to Boston for specialized treatment.

Gabriel Lafitte, the Australian researcher who was detained with Meston, said the men faced sleep depravation, long interrogations, intimidation, and threats from the state security agents who held them. Lafitte said that Meston was so terrified during the interrogations that he could barely function, and that he seemed to be driven "over the edge."

The Chinese citizen detained with Meston and Lafitte, Tsering Dorje, 26, an ethnic Tibetan who was serving as the pair's Chinese language translator, remains held at an undisclosed location.

Mike Jendrzejczyk, director of the Washington office of Human Rights Watch, said the World Bank and the United States government have both made appeals for Tsering Dorje's release, but that Chinese officials have not even acknowledged that he is being held.

"We are quite concerned about his possible mistreatment," Jendrzejczyk said.

Meston and Lafitte were in China conducting research on a proposed World Bank program that would fund the resettlement of 58,000 impoverished farmers to an area with better agricultural prospects. Tibetan rights groups say the project would dilute the Tibetan population in remote Dulan county and harm the environment, and the bank voted in June to delay funding.

After he was detained, Meston feared that in addition to incurring charges for the current trip, he would be punished for an earlier trip to Tibet that infuriated Chinese officials, Lafitte said.

Meston, who speaks Tibetan, was the interpreter for an unauthorized fact-finding mission to Tibet in 1997 led by Rep. Frank R. Wolf (R-Va.). China requires special permission for officials to travel to Tibet. Wolf, Meston and an aide traveled as tourists and Wolf gave a harsh report on China's human rights abuses in the area.