Nine Chinese oil workers have been kidnapped in Sudan, a Chinese diplomat in the capital, Khartoum, has said.
The men, and their two Sudanese drivers, were abducted in the southern Kordofan state on Saturday afternoon.
The unidentified kidnappers later released one of the local drivers with a note saying they wanted a share in the region's oil wealth.
It is the third time in the last year that oil workers have been abducted in the energy-rich region.
The men were taken from an oil field, near the district of Abyei, owned by the Greater Nile Petroleum Operating Company, a consortium of four oil companies from China, India, Malaysia and Sudan.
"One driver was released and handed over a note by the captors demanding a settlement through a share of oil production," an unidentified diplomatic source told the Reuters news agency.
"We are doing our best efforts to find them," Chinese Ambassador to Sudan Li Chengwen told the Associated Press news agency.
Ali Yousuf, director of protocol at the Sudanese foreign ministry, told AFP news agency that Sudanese forces were searching the area, but no contact had been made with the kidnappers so far.
The incident occurred near the region of Darfur, where ethnic African rebels are fighting Arab-dominated government forces.
The Darfur rebels, who accuse Beijing of indirectly helping to fund the Sudanese government's military operations in the area through oil revenues, have in the past attacked Chinese oil fields and kidnapped foreign workers.
Diplomats say the abductors were probably from the same tribal group which seized four Indian oil workers in mid-May.
One man was later released and two others managed to escape. The fourth man is believed to have escaped but was never found.