Nine assailants wielding axes and knives were shot dead after they killed two police officers during an attack on a police station in China’s restive Xinjiang region, state media reported.

The assault happened about 5.30pm (7.30pm AEST) on Saturday in the Serikbuya township of Bachu county in Kashgar Prefecture, police told the Xinhua news agency.

Xinhua said the attackers were armed with knives and axes and that two other police officers were also injured.

But Dilxat Raxit, a spokesman for Munich-based advocacy group World Uyghur Congress, said the attackers – believed to be Uyghurs, a Turkic ethnic group – were protesting and that armed Chinese personnel were to blame for the violence.

He said in an email “several tens” of Uyghur demonstrators were arrested.

“I again call on international society to take emergency measures to stop the Chinese government from directly opening fire to suppress Uyghur protesters and depriving them of using legal appeals and defending their rights,” he said.

The incident comes at a time of heightened tensions within Xinjiang following a fiery attack in Beijing’s Tiananmen Square in October that the government blamed on “terrorists” from the province backed by international Islamist militants.

Three Xinjiang Uyghurs drove their car loaded with petrol canisters into the gate of the Forbidden City on October 28. The attack killed five people, including those in the car, and injured 40, Chinese police said.

Beijing blamed Uyghur separatists backed by the violent Islamist militant East Turkestan Islamic Movement.

But authorities have not provided evidence to support this assertion, which has raised doubts among experts, given the amateurish nature of the attack and the lack of an established Islamic extremist foothold in China.

Chinese state-run media have reported bouts of violence in Xinjiang which Beijing often describes as terrorist attacks.

The mainly Muslim Uyghurs, the largest ethnic group in Xinjiang, routinely complain of rights abuses against them and dismiss claims of terrorism and separatism as an excuse by Beijing to justify religious and security restrictions.