China's Urumqi city in chaos

Thousands of angry Han Chinese armed with poles, meat cleavers and other makeshift weapons stormed through Urumqi Tuesday as the flashpoint city riven by ethnic tensions descended into chaos.

Heavily armed security forces fired tear gas at the crowds and ordered a night curfew in an effort to restore calm in Urumqi, the capital of China's remote northwest Xinjiang region where 156 people died in weekend clashes.

But tensions remained at boiling point, with Han Chinese roaming the city wielding machetes, bricks, chains, steel bars and other weapons while calling for revenge against Muslim Uighurs who they blamed for Sunday's carnage.

"The Uighurs came to our area to smash things, now we are going to their area to beat them," one protester, who was carrying a metal pipe, told AFP.

Sunday's unrest, which also left more than 1,000 people injured, began with protests by Xinjiang's Uighurs, who have long complained of repression under Han Chinese rule.

Chinese authorities have blamed exiled Muslim Uighurs for masterminding the unrest -- charges they deny -- and announced Tuesday they had arrested 1,434 suspects for murder, assault, looting and other crimes linked to the unrest.

But Han Chinese in Urumqi declared they were not satisfied with the government response.

"It is time we looked after ourselves instead of waiting for the government," said Dong Sun, a 19-year-old leader of one mob.

Police prevented the crowds, one of which an AFP reporter estimated was more than 10,000-strong, from entering Uighur neighbourhoods by firing tear gas and erecting barricades.

But in other areas of Urumqi police and other security personnel simply looked on as mobs swept through the streets shouting nationalist slogans.

The mobs roamed Urumqi all afternoon and by early evening many were still seen walking the streets carrying their weapons.

The only incident of direct violence against a Uighur that AFP witnessed was when a small mob stopped a car being driven by a Uighur man. The mob smashed his car but the man was able to drive off.

There were no reports from Chinese state media of direct violence against Uighurs.

Xinjiang Communist Party chief Wang Lequan called for calm as authorities announced a night-time curfew.

"Neither the Han nor Uighur people are willing to see the Han people being attacked," Xinhua news agency quoted Wang Lequan as saying.

"It is the same the other way around. If the Han people attack the innocent Uighur people, it is also heart-breaking."

Earlier Tuesday, more than 200 Uighurs, mostly women, staged a protest in front of foreign reporters to demand the release of their relatives detained in the security sweep that followed Sunday's unrest.

The women, with tears rolling down their faces, shook their fists in the air and yelled at police in a tense stand-off that lasted about an hour before ending peacefully.

China's eight million Uighurs are a Turkic-speaking people who have long complained about the influx of Han Chinese into what they regard as their homeland, a vast area of mountains and deserts that borders Central Asia.

Exiled Uighur groups have sought to lay the blame for Sunday's violence on Chinese authorities, saying the protests were peaceful until Chinese security forces over-reacted and fired indiscriminately on crowds.

China has accused exiled Uighur leader Rebiya Kadeer of masterminding the violence but she has denied the accusations and called on Monday for an international probe into the violence.

"We hope that the United Nations, the United States and the European Union will send teams to investigate what really took place in Xinjiang," Kadeer told reporters in Washington, urging a forceful response from the White House.

White House spokesman Robert Gibbs, in a brief statement issued from Moscow during US President Barack Obama's visit there, said the United States was "deeply concerned" about the reports of deaths in Urumqi.

The statement called for "all in Xinjiang to exercise restraint".

The identities of those killed and injured in the riots remained unclear on Tuesday. Chinese authorities have not said how many were Han Chinese or Uighur.