Four Sudanese have been sentenced to life in prison for killing a Chinese worker in oil-producing South Kordofan, state-linked media reported on Monday.

The Sudanese Media Centre (SMC), which is close to the security apparatus, did not say when the incident occurred and did not identify the victim.

But it reported that an anti-terrorism court in Khartoum North convicted the four of attacking a camp and killing the worker in Baleela, an oilfield in the western part of South Kordofan state.

Insurgents are active in the state but primarily in the eastern half.

SMC said the thieves exchanged fire with camp security men, leading to the death of the Chinese man.

One other accused was freed for lack of evidence, SMC said.

China is a major investor in Sudan's oil industry and is also a key military supplier to the cash-strapped African nation.

Beijing's embassy spokesman could not be immediately reached for comment.