Chinese leaders bowed to public demands and sacked the head of a western city wracked by communal violence and a bizarre string of needle attacks, hoping to calm uneasy mobs and end protests that percolated for a third day yesterday.

The removal of Urumqi's Com-munist Party Secretary Li Zhi came amid reports of police again dispersing crowds outside Urumqi's government offices using tear gas, and more unconfirmed reports of needle attacks, including one on an 11-year-old boy in a downtown square.

The city's chief prosecutor announced further details about four people arrested over the attacks, but offered little to back up the government's claims that they were an organised campaign to spread terror.

Protesters marched by the thousands Thursday and Friday demanding the resignation of Li and his boss, Xinjiang party secretary Wang Lequan, for failing to provide adequate public safety in the city. Also sacked was the police chief of Xinjiang, China's westernmost region that abuts Central Asia and whose capital is Urumqi.

An Urumqi government spokeswoman and the official Xinhua News Agency gave no reasons in announcing the changes. But July's riot was the worst communal violence in more than a decade in Xinjiang - where Uighur separatists have waged a sporadically violent campaign for a homeland. The renewed protests this week underscored the difficulties authorities were having in reasserting control.

Sacrificial lamb

The firing may also help quash calls to dismiss Wang - a member of the country's ruling Politburo and an ally of President Hu Jintao.

"I would say that this is the sacrificial lamb," said Russell Leigh Moses, an analyst of Chinese politics based in Beijing. "But it will be interesting to see what the reaction in the streets is and whether this satisfies people's anger or not."