A court in China has sentenced two men to death over violent unrest in the ethnically divided western region of Xinjiang that left 21 people dead, state media said Monday.

China blamed the April 23 violence on "terrorists", a charge rights groups say is often used to justify the authorities' use of force against members of the mostly Muslim Uighur minority.

The Intermediate People's Court in Xinjiang's Kashgar Prefecture sentenced Musa Hesen and Rehman Hupur to death for crimes including murder and taking part in a "terrorist group", the Xinhua news agency reported.

Hesen was accused of leading the group and manufacturing explosives.

Another three men accused of belonging to the group were given prison sentences ranging from nine years to life, Xinhua reported.

All of the defendants reportedly confessed to their crimes in court.

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.

Xinjiang, a region about twice the size of Turkey, is home to around nine million ethnic Uighurs, many of whom complain of religious and cultural repression by Chinese authorities. The region is regularly hit by unrest.

Violent riots involving Uighurs and members of China's Han ethnic majority in Xinjiang's capital Urumqi in 2009 killed around 200 people, leading the ruling Communist Party to tighten surveillance and boost investment in the region.