Security forces in China’s strife-torn western city of Urumqi have used tear gas to break up another day of protests by thousands of Han Chinese.They are demanding better security, amid claims they are the targets of mysterious attacks with hypodermic syringes. The Han protesters also say authorities have been too slow to punish Uighurs after ethnic riots in July in which at least 197 people died. Tensions have remained high despite a heavy police presence. Panic spread after government text messages warning of needle attacks. The health office in the Xinjiang region says that over the past two weeks, nearly 500 people have gone to hospital reporting apparent syringe stabbings, almost all Han Chinese. Regional TV said doctors “found clear syringe marks in 89 cases.” Demonstrators demanded the resignation of the regional Communist Party Secretary Wang Lequan who tried desperately to calm the crowds. Xinjiang’s population is divided mainly between Uighurs, a largely Muslim people culturally tied to Central Asia and Turkey and Han Chinese, the main ethnic group in China as a whole.