The capital of Northwest China's Xinjiang Uyhgur Autonomous Region, had witnessed a series of syringe stabbings last month.

Initial tests on victim's samples have found no traces of viruses or chemicals. Authorities in Urumqi have held a press briefing on the latest information regarding the attacks.

Qian Jun, head of the disease control and biological security office in China's Academy of Military Medical Sciences, says tests on samples from syringe attack victims have not found toxic chemicals or the HIV virus.

Qian Jun, Director of Academy of Military Medical Sciences, , said, "Local and military medical experts have re-checked about 250 victims and found no worsening symptoms or serious illnesses. But many of the victims are frightened from the possibility of hidden infections. I have suggested that psychological counseling be offered to ease anxiety and depression."

Wang Wenxian, deputy director of the Urumqi city public security bureau, says the needle attacks did not cause serious damage to the public's health, but created widespread panic and disturbed social order. He says the actions violated China's Criminal Law and that perpetrators will be severely punished.

Wang Wenxian, deputy director of the Urumqi city public security bureau, said, "More police and armed police forces will patrol the city's streets and strengthen surveillance at populated areas and public venues. We will do our best to track down the criminals of the attacks as soon as possible."

On September 2nd, police detained 15 people who were suspected of being involved in the syringe attacks.

Local authorities have confirmed 531 victims, with 171 showing clear indications of syringe marks. Officials say the majority of the victims were of the Han ethnic group.

(CCTV September 14, 2009)