Authorities in China's far western Xinjiang said Sunday they will send more than 7,000 officials to 110 communities in the regional capital of Urumqi to help ease panic and tension after syringe attacks led to mass protests.

They also vowed to give syringe attackers harsh punishment according to the law, ranging from three years in prison to life sentence or even death penalty.

"The officials will go door to door to explain policies and solve disputes," said Wang Lequan, secretary of Xinjiang Uygur Autonomous Regional Committee of the Communist Party of China (CPC) late Sunday.

The regional government had earlier sent 1,500 such officials and police officers to communities densely populated by Uygurs in wake of a deadly riot on July 5.

"These officials have done a great deal of face-to-face educational work in communities and maintain social orders," he said.

The move is an important "treasure" to smash the separatist sabotage of the "three forces" of extremism, separatism and terrorism both at home and abroad, the regional party chief said.

Wang made the remarks at a meeting for mobilizing civil servants to go to the grassroot neighborhoods to help solve public disputes and maintain social stability.

He reviewed the unrest in Urumqi since the riot on July 5, which left nearly 200 people dead, mostly ethnic Han people.

He said four suspects stabbed a Han woman with syringe needles in Xiaoximen Shopping Area in Urumqi on September 3, sparking mass protests that demanded security guarantees.

The protests left four dead and 14 others hospitalized.

"The incident has seriously affect the normal public life, and caused social disturbance," he said.

The situation in Urumqi is on the whole stable, but it is also fragile as demands of some residents have not been met and the sporadic occurrence of needle attacks continue to ignite sentiments, Wang said.

The control and mandatory measures, which bring inconvenience and ignite people's sentiment, could spark mass gatherings anytime, he said.

By Friday, local health and police authorities had confirmed 531 victims of hypodermic syringe stabbings, 171 of whom showed obvious signs of needle attacks.

The majority of the victims are of the Han ethnic group and the minority are from the ethnic groups including Uygur, Hui and Kazak, Wang said.

Medical experts have ruled out the possibility that radioactive substances, anthrax and toxic chemicals were used in recent needle attacks.

He also called on local residents not to believe and spread rumors and to express their demands through legal channels.

The social order had returned to normal after the July 5 riot, but the enemies at home and abroad were not reconciled to failure and so they conducted the needle attacks to spark public panic and anger, Wang said.

The mass protests have affected normal life and production in Urumqi and put to test the unity, stability and harmony that people of all ethnic groups have been seeking and longing for for years, the official said.