BEIJING: Nine suspects have been taken into police custody over alleged syringe attacks in parts of China's tense Xinjiang region, after hundreds were stabbed in Urumqi city, state media said Friday.

Six were held this week in Hotan, two in Altay and one in Kashgar, the China Daily reported, citing police and local government officials.

The report said that while several syringe attacks had been reported in each city, more than half of them had not been confirmed or turned out to be "false alarms".

Authorities in Urumqi, the Xinjiang regional capital, have detained a total of 45 people on suspicion of carrying out needle attacks in the city since mid-August.

Of the more than 500 stabbings confirmed by police, 171 victims have shown "obvious" signs of an attack, the China Daily said. Officials have said they have so far seen no evidence that the syringes contained dangerous substances.

The attacks sparked mass protests earlier this month in Urumqi, with demonstrators demanding that the government do more to ensure public safety. Five people were killed, according to officials.

The head of the Urumqi branch of the Communist Party and Xinjiang's top police official were both sacked in the wake of the needle attacks and subsequent protests.

The syringe stabbings have caused ethnic tensions to spike once again in the city, the scene of unrest on July 5 that pitted Xinjiang's minority Uighurs against members of China's dominant Han ethnic group.

Nearly 200 people were killed in the violence, most of them Han Chinese.

One official with the Xinjiang public security department, Du Xintao, has dubbed the needle stabbings "terror attacks". Han residents of the city have said Uighurs are to blame.