By Rupert Wingfield-Hayes BBC correspondent in Beijing

Chinese authorities have ordered the top university in the western province of Xinjiang to stop teaching courses in the local Uighur language.

University officials say the change is needed to raise the standard of education at Xinjiang University but Uighur groups are condemning the change as a direct attack on their culture and identity.

For more than 50 years, Xinjiang University has offered its students the choice of learning in Chinese or Uighur, the native tongue to most of the province's Muslim population.

But from this September that choice will end.

The dean of Xinjiang University confirmed to the BBC that in future all first- and second-year courses will be taught exclusively in Mandarin Chinese.

Uighurs fear their culture and society could disappear

The dean says the change is needed to raise the level of education of local Uighur students who, he says, often fall far behind their Han Chinese classmates.

He says there are also few textbooks translated into Uighur and that students who learn in Mandarin have a better chance of getting a job when they graduate.

But Uighur exile groups are calling the change an open attack on Uighur culture.

More than half of Xinjiang's population are Uighurs.

They are ethnically Turkic and they have little affection for their Chinese rulers.

Exile groups say the change is part of a concerted campaign by the Chinese Government to stamp out nationalist sentiment among Xinjiang's Uighur population.

They say the Chinese Government is using the 11 September attacks against the United States as a pretext to suppress all forms of dissent by the Muslim population of Xinjiang.