Urumqi: Han Chinese armed with iron bars and machetes roamed Urumqi city yesterday looking for Muslim Uighur targets to wreak revenge for bloody ethnic clashes two days earlier which killed 156 and wounded over 1,000.

Outnumbered riot police used tear gas to try to disperse thousands of angry protesters who flooded the capital of the northwestern region of Xinjiang.

In a sign of government anxiety about the unrest the city's Communist Party boss Li Zhi took to the streets to plead with them to return home, and overnight "traffic restrictions" - originally announced as a curfew - came into effect to halt the violence, in which many people were injured.

Security forces intervened to stop casualties, breaking up a battle between hundreds of rock-throwing Han and Uighurs and forcing a Han mob to leave a building they stormed in a Uighur area. There were no reports of deaths.

But riot police stood warily by as crowds vented their anger by throwing rocks at a mosque, and smashing shops and restaurants owned by Uighurs, a Turkic people who are largely Islamic and share linguistic and cultural bonds with Central Asia.

"They attacked us. Now it's our turn to attack them," a Han man in the crowd said. He refused to give his name.

The crowd had armed themselves with an improvised arsenal of meat cleavers, metal rods and spades seized from building sites, rocks and wooden clubs, and the most extreme shouted "kill them" and "exterminate the Uighurs".

Rioters said they wanted revenge for violence on Sunday. Beijing has not given a breakdown of the ethnicity of the dead, but official media reports initially focused on Han victims and Urumqi's Han community seem sure they were the main targets in the country's worst unrest for years.

Xinjiang has long been a hotbed of ethnic tensions, fostered by a yawning economic gap between Uighurs and Han Chinese, government controls on religion and culture and an influx of Han Chinese migrants who now are the majority in most key cities.

Beijing has poured cash into exploiting Xinjiang's energy deposits and consolidating its hold on a strategically vital frontierland that borders Pakistan, Afghanistan and Central Asia.