BEIJING – A court in China's restive far western region of Xinjiang sentenced three ethnic Uighurs to death on Thursday for acts of "violent terrorism", including murder and being part of a terrorist organisation, state media reported.

One other defendant was sentenced to 25 years in jail for his part in a June outbreak of violence, the official Xinhua news agency said.

All four were ethnic Uighurs, judging by their names.

China labelled the June incident, in which 35 people died, a "terrorist attack" by a gang engaged in "religious extremist activities".

It was the deadliest outbreak of violence in the troubled region since July 2009, when nearly 200 people were killed in riots pitting Uighurs against ethnic Chinese in the region's capital Urumqi.

Violent discontent among the region's indigenous Muslim Uighurs had for some time been confined to southern districts.

But the June altercations in Shanshan county, in which state media reported gangs attacked a police station and a government building and set fire to police cars, marked a return of unrest to Xinjiang's north.

Xinhua said the accused had been involved in illegal religious activities and had been spreading religious extremism, which led to them decide to set up a terror cell and plan attacks.

"The methods used were merciless in the extreme and the incident had serious consequences so ought to be severely punished in accordance with the law, hence the sentences," the report cited the court judgement as saying.

Many of the Turkic-speaking Uighur people chafe at what they call Chinese government restrictions on their culture, language and religion. China says it grants Uighurs wide-ranging freedoms and accuses extremists of separatism.

Many rights groups say China has long overplayed the threat posed to justify its tough controls in energy-rich Xinjiang, which lies strategically on the borders of Central Asia, India and Pakistan.