China's minority Uighur community, the majority of whom live in the northeastern autonomous region of Xinjiang, fear they could be left isolated by Chinese government plans to modernise and develop the region economically.

This region is the country's largest natural gas-producing areas but as Al Jazeera's Melissa Chang reports from Kashgar, it is also one of the poorest.

The Uighurs, a Muslim Turkic ethnic group who have long complained they are victims of government discrimination and repression, say China's declaration of Kashgar, a city in Xinjiang, as a Special Economic Zone, will probably benefit the country's predominant Han Chinese at their expense.

They say their jobs and land are under threat as a consequence of a massive influx of Han Chinese migrants.

Meanwhile, courts in Xinjiang have sentenced four Uighurs to death on Tuesday for their role in violence that left 32 dead in July, the regional government said in a statement on its official website.

The government blamed so-called religious separatists for "terrorism, arson and murder" in the region's cities of Kashgar and Hotan. It also said they aim to establish an independent state called East Turkestan.

But the World Uighur Congress, a Germany-based exile group, said the convicted had been tortured while in detention and were given only very limited access to lawyers.

"The so-called open trial is a special type of Chinese political swindle," Dilxat Raxit, spokesman of the group, said in an statement.

Geoff Crothall, a researcher at the China Labour Bulletin, a rights group, said social problems and ethnic tensions in the region would probably escalate as the government implements new economic projects there.

"If you just look at the population figures of Xinjiang, only two million people there actually have a residency card, while about 12 million others are just migrant workers," he told Al Jazeera.

"The Uighurs, the indigenous group in Kashgar, are going to be subject to a flood of Han Chinese as well.

"Because it's always the Han Chinese migrant workers who build the new office buildings, new factories, and that is clearly going to create further tension in the future."