Sudan's security forces have freed a Chinese worker abducted last week in the conflict-hit West Kordofan region, the oil minister said on Friday.

"The security apparatus has been working day and night to reach the perpetrators and free the hostage," Oil Minister Makkawi Mohamed Awad said in a statement carried by official SUNA news agency.

The Chinese embassy in Khartoum did not immediately comment on the incident.

In the same operation, security forces captured the alleged killers of a Sudanese engineer who was shot last week near the town of Baleela in the same southern region, the minister said.

The statement gave no further details on the kidnapping or the engineer's murder.

Sudanese media reported last week that unidentified gunmen killed a senior engineer at an oilfield near Baleela and wounded several of his bodyguards, without mentioning the Chinese national.

Government forces are battling insurgents in the West Kordofan region, which is Sudan's main oil-producing state. In April, armed militants kidnapped two Chinese nationals and an Algerian from another oilfield.

No group has claimed responsibility for the abductions.