Several knife-wielding attackers killed four people and wounded eight others in China's ethnically-divided western region of Xinjiang, a government official said on Friday.

Regional spokeswoman Hou Hanmin said the attackers were members of the Uighur ethnic group. They often have tense relations with the millions of Han Chinese who have moved to the region in search of jobs.

The attack occurred on Thursday in Korla, in the centre of Xinjiang, Hou said, adding that one of the assailants had been detained and police were searching for the others.

She did not identify the ethnicity of the victims, or whether the attack was politically motivated. Chinese leaders are currently gathered in Beijing for the annual meeting of the National People's Congress, a rubber-stamp parliament.

Riots between Uighurs and Han Chinese in Xinjiang's capital Urumqi in 2009 killed around 200 people, leading the ruling Communist party to tighten security and boost investment in the region.