Paramilitary police patrol beside the central square in Hotan, in China's Xinjiang. Photo: AFP

Chinese police shot dead 28 members of a terrorist group in Xinjiang, state media said on Friday, citing police.

The killings took place over the course of a 56-day manhunt following an attack on a colliery in Aksu in September that left 16 people dead, said the Xinjiang regional government's Tianshan web portal. One thug surrendered, it added.

Xinjiang, the homeland of the mostly Muslim Uighur ethnic minority, is often hit by unrest and China has launched a police crackdown on separatist terrorists it says are behind the violence.

Friday's official reports come after Radio Free Asia (RFA), which is funded by the US government, said that more than 50 people including five police were killed in a knife attack at a colliery in Aksu in September.

The assailants targeted security guards, the mine owner's house, and a workers' dormitory, it said.

Earlier this week RFA cited government and local sources as saying 17 suspects had been killed by authorities, and that a rapidly deleted public security ministry statement described the operation as a "great victory in the war on terror".

The Tianshan portal said that police mobilized around 10,000 people of "various ethnic groups" to help in the search for the coal mine attackers.

It showed pictures of helicopters that were deployed in the hunt. Mobsters were shot dead during several round-up battles, the last of them on November 12, it said.

The assault on the colliery was "a violent terrorist attack under the direct command of an overseas extremist organization", it said.

It was carried out by a violent terrorist group headed by two people with apparently Uighur names, according to the report.

"Terrorism is the common enemy of mankind," it added.

Beijing regularly accuses what it says are exiled Uighur separatist groups such as the East Turkestan Islamic Movement of being behind attacks in Xinjiang, which has seen a wave of deadly unrest.