The Chinese authorities say the man, Gabriel Lafitte of the Australia Tibet Council, and an American had been investigating a resettlement project in Dulan County near Tibet when they were detained on 13 August.

Chinese officials say the American, Daja Meston, a linguist who grew up in Tibetan monastery in Nepal, was taken to hospital after he fell from a third floor window while trying to escape from police custody.

He is reported to have suffered a broken back and severe internal organ damage from the fall, but is now said to be out of danger following surgery.

A team of US officials have spoken with Mr Meston in hospital in the provincial capital Xining in an effort to uncover whether he was the victim of official abuse.

State of mind

Pressure groups say China is trying to wipe out indigenous cultures

Mr Meston's Tibetan wife has said she could not understand what circumstances would drive her husband to take such action.

"He is normally a very calm and strong person," the London-based Tibet Action Network quoted her as saying. "It is terrible for me to imagine his state of mind if he was driven to do such a thing."

Chinese security officials had accused the two men of engaging in an "illegal investigation", having entered the country on tourist visas, but later said Mr Lafitte had "confessed, apologised and repented" after which he was released from custody.

Controversial project

The region is close to the birthplace of the Dalai Lama

The Dulan County relocation program is linked to a controversial World Bank poverty project, which is opposed by the United States and Tibetan exile groups.

The groups say Beijing is populating pro-independence Tibetan regions with thousands of Chinese settlers in a project that could reignite violent ethnic hostilities, wipe out Tibetan culture and damage the fragile environment.

The area is also near to the birthplace of the Dalai Lama who lives in exile in India.

The World Bank has loaned China $160m for the project, but has imposed a temporary freeze on the resettlement money until a panel reviews whether the decision violates the Bank's own rules.

There are also concerns that the project could damage the region's fragile environment

The US State Department says it believes the two men were conducting interviews in Dulan County as part of an independent study of the project's impact.

World Bank spokesman Peter Stephens said the organisation had been in high level contact with Chinese officials on behalf of the two men following pressure from several US congressmen.

Mr Meston had previously worked as a translator for Congressman Frank R Wolf (R-Viginia) during an unauthorised trip to Tibet in 1997.