Chinese police have killed eight people after a "terrorist attack" in the country's northwest Xinjiang region, the regional government said.

The eight people were shot dead on Monday following an attack on a police station in Yarkand county, close to the old Silk Road city of Kashgar, the government said in its official news website statement.

"At around 6.30am, nine thugs carrying knives attacked a police station in Kashgar's Yarkand county, throwing explosive devices and setting police cars on fire," the brief statement said.

"The police took decisive measures, shooting dead eight and capturing one," it added, labelling the incident a "violent terrorist attack."

Earlier this month, police gunned down 14 people during a riot near Kashgar that also killed two policemen.

And at least nine civilians and two policemen were killed in a separate outburst last month when people armed with axes and knives attacked a police station, also near Kashgar, state media said.

China has blamed some of the violence in Xinjiang on its substantial Muslim population, who they say are plotting a holy war in the region.

Region of unrest

Human rights groups have criticised the heavy-handed tactics used by police against the Muslim Uighur community, a Turkic ethic group that calls the region home.

Violence has broken out in the past when members of the Uighur community have protested at police stations.

Xinjiang has been the site of numerous incidents of unrest in recent years, which the government often blames on the separatist East Turkestan Islamic Movement, a group founded by the Uighurs.

But rights groups have said China overplays the threat posed by Uighurs to justify its tight control over energy-rich Xinjiang, which lies strategically on the borders of Central Asia, India and Pakistan.

China recently increased security in Xinjiang after a vehicle ploughed into tourists in Beijing's Tiananmen Square in October, killing five people.

The government blamed "Islamic militants" for the attack.

Xinjiang's Turkic-speaking Muslims are offended by restrictions the government places on their culture, language and religion.

Authorities are investigating Monday's attack further.