The Chinese government has been encouraging mass Han Chinese migration to Tibet, which, it says, is helping the region to improve economically.

According to Chinese government statistics, Tibet's GDP in 2003 was about 28 times what it was in 1978. But Tibetans complain that those who predominantly benefit from the growth are the Chinese migrants who then send the money back home.

The proportion of Han Chinese in the TAR has risen sharply, although Tibetans still make up about 93% of the population. However, the Han influence is disproportionate, Tibetans say, with Chinese dominating its economy and other spheres of influence, and threatening the area's cultural identity.

This change is likely to intensify following the opening of the Golmud-Lhasa railway, which is expected to significantly increase Han Chinese traffic to Tibet.

The Tibetan government in exile has pointed to comments by former President Jiang Zemin to the New York Times in August 2001, which make clear that the railway is intended to be a predominantly political, rather than economic, investment.

"Some people advised me not to go ahead with this project because it is not commercially viable. I said this is a political decision, we will make this project succeed at all costs, even if there is a commercial loss," Mr Jiang told the paper.