China on Sunday vowed a year-long campaign against terrorism, days after attackers in the western region of Xinjiang killed 39 people in a suicide raid.

"With Xinjiang as the centre, and with cooperation from other provinces, we will start a year-long specialised hard-strike campaign against violent terrorism," the ministry of public security said on its website.

The statement reflects the government's concerns about terror after a series of deadly attacks in recent months targeting civilians and linked to Xinjiang, home of the mostly Muslim Uighur minority.

It indicates a nationwide expansion of a year-long crackdown in Xinjiang, which authorities announced Saturday.

Five suspects carried out the attack on Thursday in Xinjiang's capital Urumqi which "killed 39 innocent people" and injured more than 90 others, the state-run Xinhua news agency said.

One suspect has been arrested, Xinhua said, while four others died when they crashed cars into a marketplace and threw explosives.

The statement said the campaign would last until June 2015 and is aimed at "preventing the spread of religious extremism" from Xinjiang to the country's interior.

Police were instructed to "collect clues related to violent terror" under the direction of an anti-terrorism "leading small group", which is likely to include high-level officials from the ruling Communist party.

In a separate report Sunday, the state-run Legal Daily said police in the Xinjiang cities of Aksu, Hotan and Kashgar had "busted" 23 terror groups this month.

They arrested more than 200 suspects and confiscated 200 explosive devices, it added.

An unidentified number of suspects were detained in those areas this weekend for "watching terrorist videos and spreading religious extremism", it said.

The United States and the United Nations condemned the violence in Urumqi, whose residents were shocked by the carnage.

Beijing says it faces terrorism from a violent separatist movement in Xinjiang, driven by religious extremism and foreign terrorist groups.

But it is unclear how organised the militant groups in Xinjiang are, or whether they have links to foreign organisations. China tightly controls reporting in the region, making independent information scarce.

Rights groups point to economic inequality and cultural and religious repression of Uighurs as drivers of unrest in the vast and resource-rich far-western region which abuts Central Asia.