SHANGHAI: Chinese police have shot dead four people suspected of making bombs in the far western region of Xinjiang, which has been beset by ethnic strife and violent unrest, Radio Free Asia reported on Saturday.

The pre-dawn raid on a farmhouse took place on Thursday after a man was injured while making a bomb at home, which raised suspicions; the US-based broadcaster quoted local police as saying.

China has blamed violence in Xinjiang on Islamic separatists who want to establish an independent state called East Turkestan.

Exiled Uighur groups and human rights activists say China overstates the threat posed by militants in Xinjiang, which sits astride south and central Asia.

Twenty-one people were detained by police in Thursday's raid, during which one of the suspects chopped off a policeman's hand with an axe, Radio Free Asia said.

Last month, the government said attackers wielding knives killed 13 people in Xinjiang before police killed seven of them.

Uighurs account for just over 40 per cent of the Xinjiang region's 21 million people. But they are the majority in Kashgar and other parts of the region's south and many resent government controls on their culture and religion.

In July 2009, Uighurs rioted against Han Chinese residents in Urumqi, the capital of Xinjiang. At least 197 people were killed, most of them Han, according to official estimates.

In January, authorities said that seven people killed by police in Xinjiang had been trying to leave the country to wage “holy war”.

The government sees Xinjiang as a bulwark facing the predominantly Muslim countries of central Asia. The region, with a sixth of the country's land mass, is also rich in natural resources, including oil, coal and gas.