BEIJING - China formally indicted a prominent ethnic Uighur professor for separatism on Wednesday, as security forces flooded into the far western region of Xinjiang amid more reports of violence following what the government called a terrorist attack.

Police in Beijing in January detained Ilham Tohti, a well-known economist who has championed the rights of the Muslim Uighur community, who come from Xinjiang.

He was subsequently taken to the regional capital Urumqi and accused of promoting and supporting Xinjiang's independence from China, a red line for Beijing which views the region as an inseparable part of the country.

A brief statement on the official microblog of the Urumqi prosecutor said that Tohti's case had been turned over to a city court, the next legal step needed before he can be put on trial.

It gave no details.

His wife has denied the allegations, and the case has attracted high-level concern in the United States and Europe.

The case against Tohti is the latest sign of the government's hardening stance on dissent in Xinjiang, where unrest in the past year or so has killed more than 200, including several police, according to state media.

Western tourists saw a body lying in a pool of blood in a major Xinjiang city on Wednesday, as well as a heavy security presence after the government said dozens of knife-wielding attackers were shot dead elsewhere in the region earlier in the week.

State media said a gang armed with knives first attacked a police station and government offices on Monday in the town of Elixku, in Shache county, about 200 km (125 miles) from the old Silk Road city of Kashgar in China's far west.

Some moved on to the nearby town of Huangdi, attacking civilians and smashing and setting fire to six vehicles, in what the official Xinhua news agency called an "organised and premeditated terrorist attack".

"Police officers at the scene shot dead dozens of members of the mob," the brief report said.

Xinjiang, home to many Turkic-language speaking Uighurs, has been beset by violence for years, which the government blames on Islamist militants or separatists who it says are bent on establishing an independent state called East Turkestan.

There were indications that unrest had spread by Wednesday to Kashgar, a popular tourist site especially during the summer.

A French traveller said he saw a body lying outside the Id Kah Mosque in Kashgar's old town on Wednesday morning, and armed police pouring into the city by afternoon.

"We heard shouting and my friend saw two people running away with knives. Police came quickly and told people not to take pictures. They checked mobile phones," he told Reuters by telephone.

He added that the reasons for the violence were unclear and he could not tell if those involved were Uighur or members of China's majority Han ethnicity.

When leaving Kashgar on Wednesday, the traveller said a long convoy of armed police vehicles, including at least five armoured personnel carriers, drove into the city.

"All cars coming into Kashgar were being turned around," he said.

"These were urban tanks with machine guns, not water cannon," another European citizen accompanying him said.

State media only reported the attacks in Shache, also known by its Uighur name of Yarkant, late on Tuesday.

It is not clear why there was a delay, though China's ruling Communist Party, which values stability above all else, has a habit of suppressing or delaying bad news.

Reuters could not reach the Xinjiang government for comment despite repeated attempts.

The government has yet to give a full account of what happened, or a death toll.

Exiled Uighur groups and human rights activists say the government's repressive policies in Xinjiang, including controls on Islam, have provoked unrest, a claim Beijing denies.

China exercises tight control over Xinjiang, making visits by foreign reporters there to independently assess the situation extremely difficult.