An exiled leader of China's Uighur ethnic minority has condemned the death sentences passed on two people over what authorities called a terrorist attack in the restive western region of Xinjiang.

The pair were sentenced to death and three other people condemned to prison terms ranging from nine years to life on Monday by a court in Xinjiang, home to around 10 million of the mostly-Muslim minority, official media reported.

Rebiya Kadeer, leader of the World Uyghur Congress, an exile group which has been condemned by Beijing, called the sentences "politically motivated" in a statement sent to AFP late Wednesday.

The sentences "serve merely as a stark reminder from the Chinese authorities that Uighurs are not equal before the law, nor can they expect any time soon full enjoyment of their rights", she said.

Xinjiang is periodically hit by clashes between Uighurs and members of China's Han majority group. Chinese authorities often blame the violence on terrorist groups seeking independence for the region.

Those accusations are denied by Uighur exile groups, who say that violence stems from resentment caused by lack of economic opportunities as well as restrictions on religious and cultural freedom.

According to official figures, 46 percent of Xinjiang's population are Uighur while another 39 percent are Han Chinese, after millions from the majority group moved there in recent decades to find work.

A total of 19 suspects were arrested after the April incident in Kashgar's Bachu County, which saw gunfights break out leaving 15 police and community workers and six "terrorists" dead.

The trials indicated a "lack of due process and concrete evidence", the World Uyghur Congress said in a statement.

"These sentencings will only serve to foment the already seething resentment at the impunity of the way in which the Chinese authorities brutally cracked down upon Uighurs," it added.

Lawyers in China often report that they are not able to meet with their clients or examine evidence ahead of politically sensitive trials, while accusing authorities of using force to extract confessions.

Xinjiang saw its worst ethnic violence in years in July 2009 when riots involving Uighurs and Han settlers in Urumqi left around 200 people dead.