Police have installed 40,000 security cameras throughout the capital of China's Xinjiang region, state media said on Friday, as the city braces for the first anniversary of deadly ethnic violence.

The cameras have been installed in Urumqi in more than 3,000 public buses, 200 bus stations, along more than 4,000 roads, 270 schools and more than 100 large supermarkets or malls, the Xinjiang Economic Daily said.

The cameras, which are monitored around the clock from a police command centre, were installed to "ensure security in key public places, allow people of all ethnicities to enjoy quality public services, and create a peaceful capital," the report said.

Monday marks the first anniversary of bloody violence that erupted between the region's Muslim ethnic Uighurs and members of China's majority Han ethnicity.

The government says nearly 200 people were killed and about 1,700 injured in the unrest, China's worst ethnic violence in decades, with Han making up most of the victims.

Amnesty International called on the Chinese government Friday to launch an independent inquiry into the ethnic violence.

"The official account leaves too many questions unanswered. How many people really died, who killed them, how did it happen, and why?" said Catherine Baber, Amnesty International's Asia-Pacific deputy director.

Amnesty said it had new testimonies from Uighur witnesses detailing how a peaceful protest against government inaction in the face of killings of Uighur factor workers in southern China was met with violence by security forces.

"Instead of stifling inquiry, blaming outside agitators and generating fear, the Chinese government should use the anniversary to launch a proper investigation, including into the Uighur community's long-simmering grievances that contributed to the unrest," Baber said.

Xinjiang, a vast, arid but resource-rich region that borders Central Asia, has more than eight million Uighurs, and many are unhappy with what they say has been decades of repressive communist rule by Beijing.

Many also complain about an influx of Han that they say leaves them economically and culturally marginalised in their homeland.

Authorities have ramped up security in Xinjiang this year, while also promising to boost development to ease Uighur anger.

Urumqi police last month said they had launched a security clampdown to run until July 20 that would include increased police patrols and inspections of vehicles.

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