Chinese authorities say nine new suspects have been arrested in western Xinjiang as needle attacks apparently spread outside the capital of the remote region.
The official China Daily newspaper says six were held this week in Hotan, two in Altay and one in Kashgar.
Since last week, more than 500 people in the capital of Urumqi have reported attacks, though only about 100 showed evidence of being pricked.
Earlier this month, the bizarre stabbings led to mass demonstrations by thousands of Han Chinese against what protesters said was a government that was incapable of guaranteeing their safety.
Officials and state media have blamed the attacks in Urumqi on separatists bent on destroying ethnic unity.
In early July, a demonstration by Uighurs turned into a riot in which nearly 200 people, mostly Han Chinese, were killed. Han Chinese launched revenge attacks two days later.
Uighurs have long complained of discrimination by the Han Chinese, who dominate China's leadership. The Uighurs say they are denied economic opportunities and are persecuted for their different culture and religion. Beijing says it treats everyone equally.
Some information for this report was provided by AFP, AP and Reuters.