China's state media has raised to 35 the death toll from unrest this week in far western Xinjiang region, and denounced the clashes, the deadliest in four years, as a "terrorist attack", Reuters reported.

Xinjiang is home to a large Muslim Uighur community and violence focusing on its discontent had been confined recently to southern districts. The altercations in Shanshan county on Wednesday marked a return of unrest to Xinjiang's north.

Many Uighurs, Muslims who speak a Turkic language, chafe at what they call Chinese government restrictions on their culture, language and religion. China says it grants Uighurs wide-ranging freedoms and accuses extremists of separatism.

On Wednesday, June 26 gangs with knives attacked a police station and a government building and set fire to police cars. Twenty-four people died in clashes with police, including 16 Uighurs, state news agency Xinhua said.

According to Xinhua's latest dispatch on Thursday night, eight more died in the police response. It called the incident a "violent terrorist attack" and said the overall situation was now "on the whole, stable".

An officer at Shanshan county's public security, or police, bureau told Reuters by telephone that the cause of the riots and the ethnic origin of the attackers remained unclear.