Two explosions in the Xinjiang Uygur autonomous region's Aksu prefecture on Friday have been deemed terrorist attacks and the death toll has risen from three to 12, local authorities said on Saturday.

Late on Friday, local authorities said in a statement that two explosions took place at a hair salon and a vegetable market in the county seat of Xinhe at about 6:40 pm on Friday, killing one person and injuring two.

Police arrested three suspects.

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Later, a vehicle also exploded while being pursued by police, killing two people inside. According to the latest statement released on Saturday, the attackers also threw explosives at police. One officer was slightly injured. No civilian casualties were reported.

Six of the attackers were shot dead at the scene and six others committed suicide by detonating explosives. The police also arrested five people and seized a batch of detonation devices.

"Social order has been restored in the county. Police are still investigating the case to make sure all (remaining) members of the terrorist cell are in their custody," Luo Fuyong, spokesman of the autonomous region, said on Saturday.

Also on Saturday, police in Xinjiang's capital Urumqi said they have conclusive evidence proving Ilham Tohti, a Uygur economist at Beijing's Minzu University, has been involved in secession activities.

Police said Ilham's case is being processed but did not say when and where he was detained.

Ilham uses "UighurOnline", a website he set up, to spread rumors and separatist thought as well as misrepresent events to instigate ethnic hatred and call for "Xinjiang independence", the Urumqi Public Security Bureau said in a statement released on Saturday evening.

He also tells students that "Uygurs need to use violence to protest". He called those who have carried out terrorist attacks "heroes" and instigates students to hate and even "overthrow" the government.

Police said Ilham uses his status as a teacher to draw or lure people to form a group connected with key members of the overseas East Turkestan Islamic Movement that is listed as a terrorist group and sanctioned by the United Nations.

Ilham's group also helps to organize and send people abroad to carry out separatist activities.

Foreign Ministry spokesman Hong Lei said on Jan 17 that the arrest of Ilham was within the law.

"Ilham is suspected of breaking the law. Currently, China's relevant departments are handling the case according to law," he said.

"We oppose any country or party using human rights as a pretext to criticize another country's normal law enforcement."

cuijia@chinadaily.com.cn