URUMQI: Security remained tight as signs of normality returned to the restive Chinese city of Urumqi on Saturday following days of protests that have left five people dead.

The protests over a spate of mysterious syringe attacks began on Wednesday in the capital of the northwestern Xinjiang region, where ethnic unrest in July between mainly Muslim Uighurs and Han Chinese left nearly 200 people dead.

The demonstrations reached a peak Thursday when tens of thousands of people, mainly Han, poured into the streets following reports that hundreds had been stabbed with needles since mid-August. Five people were killed, officials said.

On Saturday, traffic restrictions were eased and cars, taxis and regular buses were on the roads, an AFP reporter witnessed. More shops were open than on Friday, and more residents returned to the streets.

At the Hantenggeli mosque in the city centre, which was closed Friday, an official in the management office who asked not to named said: "Yes, we are open today. Everything is back to normal. There are people inside praying now."

Thousands of security forces however remained in place in the city of 1.8 million people, with about 600 troops manning just one intersection on a road leading into Urumqi's Uighur district. A helicopter circled overhead.

At Nanhu Square, where police used tear gas to disperse protesters Friday, hundreds of People's Armed Police carrying automatic weapons with bayonets attached created a security ring around the regional government headquarters.

All of the roads leading to the giant plaza were closed.

City authorities stepped up security checks at large shopping malls and markets, warning the venues could be shut down if they failed to comply, according to the Morning News, a local newspaper.

National public security minister Meng Jianzhu, who rushed to Urumqi on Friday to oversee the security deployment, has said the syringe attacks were "instigated by ethnic separatist forces".

Beijing has long contended it faces a major Islamic separatist threat originating in the mainly Muslim region, linking Uighur dissidents to Osama bin Laden and his Al-Qaeda network.

China has said "separatists" orchestrated the deadly July unrest, which largely targeted members of the country's dominant Han ethnic group.

Minority Uighurs however say that violence was sparked when Chinese security forces reacted harshly to peaceful protests over an earlier factory brawl in southern China that state media said left two Uighurs dead.

State media, quoting police, said a total of 531 people had sought treatment in hospital after being stabbed with syringes in Urumqi since mid-August.

No one had been infected or poisoned in the assaults, Xinhua said, and it remains unclear what the syringes contained, if anything.

Police have detained 25 people over the attacks, which many of the victims have blamed on Uighurs.

The manager of one Urumqi pharmacy, who identified herself only by her surname Huang, said tight restrictions had been imposed on the sale of hypodermic needles, now only available at hospitals.

"How can we continue to sell needles? Society is so chaotic and there are so many bad people around," she said.

Meng was quoted as saying on Friday that the needle attacks were a continuation of the ethnic violence seen here in July.

"Those involved in violence, assaults, vandalism, looting and burning, and those who disrupt social order by different means or undermine ethnic unity, shall be punished according to the law without exception, whatever their ethnicity is," he said.