Xinjiang's top official of the Communist Party of China (CPC) on Thursday pledged a harsh and lasting crackdown on terrorists.

"The terrorists are the common enemies of all ethnic groups in Xinjiang and we cannot treat them with leniency," Zhang Chunxian, secretary of the CPC Xinjiang Autonomous Regional Committee who is attending an annual session of the country's top legislature in Beijing, told reporters after a panel discussion.

"The crackdown targets the terrorists, rather than the majority of people or any specific (ethnic) group," he said.

Of terrorist activities in the ethnic region, 90 percent resulted from the influence of overseas online footage, according to the official.

Zhang's remarks came days after knife-wielding assailants killed 29 civilians and injured another 143 at a railway station in the southwestern Chinese city of Kunming. Evidence linked the attack to terrorists from Xinjiang.

"The terrorists who committed the crime are totally inhumane," Zhang said. "They are indeed against humanity, society and civilization."

He said that legislation of anti-terrorism laws and regulations should begin.

"We should do everything possible to improve people's livelihood and let them enjoy the benefits of reform," Zhang said.