Beijing/Khartoum - Nine Chinese oil workers have been kidnapped by an unknown group in Sudan, state media said on Monday.

The nine workers were seized at an oil field in Southern Kordofan State close to Sudan`s strife-torn Darfur region, the official Xinhua news agency quoted Chinese embassy officials as saying.

No group has claimed responsibility for kidnapping the workers, who were employees of the China National Petroleum Corporation, the agency reported from Khartoum.

The men were taken on Saturday from an oil field owned by the Greater Nile Petroleum Operating Company, which is a consortium of the CNPC plus companies from India, Malaysia and Sudan.

Sudanese authorities accused the rebel Justice and Equality Movement (JEM) of the kidnapping, but the group, which kidnapped five foreign workers last year, has released no statement on the issue.

The Chinese embassy has implemented its emergency procedure and "held intensive contacts and consultations with the Sudanese authorities" in an effort to secure the release of the workers, Xinhua quoted an embassy spokesman as saying.

The Sudan Tribune, quoting a foreign ministry official, said that Sudanese troops were searching the area but that no contact had been made with the kidnappers.

According to the Tribune, members of a local tribe, the Messeria, are also suspected of involvement in the kidnapping in an attempt to get a greater share of the region`s oil revenue.

The Messeria were blamed for the kidnapping of four Indian oil workers in May, while the JEM last year attacked two Chinese-run oil fields in the region.

Darfur rebels have also attacked Chinese oil interests in the region.

The rebels say that China is indirectly supporting Khartoum`s military operations in Darfur through profits from the oil industry.