There has been a fresh wave of needle attacks in recent days despite heavy security in China's tense Urumqi city, state media reported on Wednesday, adding that the number of arrests had grown to 45.
Police in the capital of the northwestern Xinjiang region said they received reports of 77 needle attacks between Sunday afternoon and Monday afternoon, the China Daily said.
Authorities had previously reported a total of 531 assaults.
The attacks came despite the deployment of thousands of armed police throughout the city following large-scale protests last week in which demonstrators demanded government action to stop the attacks.
The paper said police had apprehended 10 more suspects over the needle attacks, raising the total to 45. Authorities have said some attackers could be given the death penalty if convicted of spreading toxic substances.
The attacks have caused ethnic tensions to spike once again in the city, the scene of deadly unrest on July 5 that pitted Xinjiang's minority Uighurs against members of China's dominant Han ethnic group.
Nearly 200 people died in the July violence, mostly Han Chinese.
The mainly Muslim Uighurs have long seethed at what many say has been decades of Chinese oppression and unwanted immigration of millions of ethnic Han.