An American citizen detained in China's remote Qinghai province fell from a third-story window and suffered serious injuries, China has told U.S. officials.

Daja Meston, 29, of Newton, Mass., was hospitalized in the provincial capital of Xining, two official sources said. He came to China independently to interview people about a controversial World Bank project, his wife said, and he was detained by Chinese authorities who accused him of conducting an "illegal investigation."

U.S. officials have not yet been in contact with Meston, and the circumstances of his fall are unclear. The Chinese assert that Meston was injured while attempting to flee.

"We were told he jumped while trying to escape from detention," said one source. But another added: "We obviously don't know if he did jump or was pushed or whether he was beaten or what."

China has told the State Department that Meston's injuries are serious but not life threatening. They said he suffered broken bones, one source said.

State Department spokesman James P. Rubin said Thursday that the United States has "urged the Chinese to release the American." A U.S. official was en route today to meet with Meston.

Meston, an advocate of Tibetan causes, entered China on a tourist visa in late July and was trying to learn about a plan to move 58,000 poor farmers in Qinghai to a new area with better agricultural prospects. Tibetan rights groups oppose the plan because they say it will dilute the Tibetan population in the area. Qinghai is east of Tibet and has a substantial Tibetan population.

Chinese authorities are intensely sensitive about Tibet and view criticism of their policies toward Tibetans as an effort to advance the cause of "Tibetan separatism."

Meston served as a translator on an unauthorized trip to Tibet by Rep. Frank R. Wolf (R-Va.) in 1997. China requires special permission for official delegations to travel to Tibet, and Wolf's harsh account of the human rights abuses infuriated China.