An Australian researcher who was detained along with an American citizen in China's northwestern Qinghai province seven days ago was escorted onto a plane by Chinese security agents Saturday and arrived home today.

Gabriel Lafitte said he is very concerned about the fate of a third man, a Chinese citizen, who was detained along with them, his wife Helen Verran said in an interview. Tsering Dorje, a Tibetan, traveled with Lafitte and the American, Daja Meston, as they investigated a controversial World Bank project without Chinese authorization. Tsering Dorje is being held at an undisclosed location.

Verran said her husband is also worried about Meston, who suffered a broken back and severe internal injuries when he fell from a third-floor window while in Chinese custody last week. Lafitte, 50, was escorted onto a plane by at least six security agents Saturday and sent home. Verran said she did not yet have any specific information on Meston's case.

A U.S. doctor and consular official visited Meston, 29, in a Qinghai hospital for a second time Saturday. He was so weak that he couldn't telephone his wife, said an official source. Phuntsok Meston is preparing to travel to see her husband with assistance from the State Department, the source said.

The circumstances of Meston's fall remain unclear. Chinese officials maintain that he jumped while trying to escape, but U.S. officials want to know whether he was the victim of abuse.

U.S. officials, who have been engaged in a largely private effort to secure Meston's release, have told China that they want to transport Meston to the United States whenever American doctors determine he is well enough to travel.

The Chinese government said Friday that Meston, a fluent Tibetan speaker, and Lafitte "confessed" to "illegal covering and photographing in closed areas." They were in China to research a World Bank resettlement program in Dulan county that opponents say will dilute the Tibetan population and harm the environment.

In June, the World Bank's board of directors approved the Dulan project but voted to delay its funding pending an inquiry. At the time, Zhu Xian, China's top representative to the bank, said Chinese authorities welcomed independent international scrutiny of the project.

In August 1997, Meston acted as the interpreter on an unauthorized fact-finding mission to Tibet led by Rep. Frank R. Wolf (R-Va.). China requires foreign officials and journalists to obtain special permission to travel to Tibet. The trip infuriated Chinese authorities, who blasted Wolf's report of Chinese abuses in the area.