China on Wednesday sentenced 39 people to jail terms of up to 15 years on terrorism charges, as authorities crack down on the restive far western region of Xinjiang, hit by a recent string of knife and bomb attacks blamed on Islamist separatists.

The suspects, who had ethnic Uygur names, were sentenced in a rare mass public event.

They were accused of crimes ranging from inciting violence and distributing recordings with extremist content to illegally making firearms and promoting ethnic hatred, the Legal Daily newspaper, run by the Chinese Communist Party, said.

"All those who dare to challenge the power of the state or the lives of the people, will be severely punished in accordance with the law without lenience," the paper quoted a judge of Xinjiang's high court criminal tribunal as saying.

Three people were killed and 79 others injured in an attack on a railway station in the city of Urumqi, in Xinjiang, late in May. In March, 29 were killed and 143 more were injured at a train station in the southwestern city of Kunming.

China has blamed both crimes on Islamist separatists from Xinjiang.