A mob armed with knives and axes rampaged through part of China's volatile northwestern region of Xinjiang and police responded with gunfire, leaving dozens of people dead in the latest violence blamed Islamic militants, state media reported.
Many other people were injured in the violence Monday in Shache county near the city of Kashgar, the official Xinhua News Agency said.
However, that official account was disputed by a US-based organisation representing the Uighur ethnic group, many of whom live in Xinjiang.
The Uyghur American Association said Wednesday that according to "local sources," police killed protesters condemning "Chinese security forces' heavy-handed Ramadan crackdown since the beginning of the Holy Month and extrajudicial use of lethal force in recent weeks."
Neither version could be independently confirmed.
The government account said a mob first attacked a police station and government offices in the township of Elixku before moving on to a neighbouring township, attacking civilians and smashing and setting on fire vehicles along the way.
Xinhua said dozens of people were killed or injured in the attacks but gave no precise figures. It also said that police shot and killed dozens of the attackers.
"Initial investigation showed that it was a premeditated terror attack. Further investigation is underway," Xinhua said.
Calls to more than a half-dozen police stations and government offices in the area either rang unanswered on Tuesday evening (local time) or were answered by people who confirmed the attack but said they were not permitted to release any information about it.
The Uighur association said police had already killed several in the region before Monday's incident after a July 18 protest also denouncing police repression during Ramadan.
Obtaining details of violence in the remote region is usually impossible and authorities routinely prevent foreign journalists from working freely in the area.
There has been increasing violence in Xinjiang in recent months blamed on pro-independence militants from the region's native Turkic Uighur Muslim ethnic group. While some of the attacks have shown an increased level of sophistication and planning, most have relied on crude weaponry such as swords, bombs and homemade explosives.
China's government says the attackers have ties to overseas Islamic terror groups, although it has provided little evidence to back up its claim.
Uighur (pronounced WEE-gur) activists say repressive Chinese cultural and religious policies are fuelling resentment among Uighurs, along with a sense that the benefits of economic growth in the resource-rich region are flowing disproportionately to migrants from the country's Han Chinese majority.
Also known as Yarkant, Shache is near the border with the unstable Central Asian states, about 3,500 kilometres (2,175 miles) west of Beijing.