Nigerian police said on Tuesday they had freed three Chinese workers kidnapped last week from a gold-mining site in southwestern Osun state. The Chinese were abducted and their police escort killed on February 1 following a dispute with local labourers at the mining site at the Atakumosa area of the state. "We have rescued the three Chinese expatriates. They were freed on Sunday," state police spokeswoman Yemisi Opalola told AFP. She said they were released following a joint operation of police and local hunters. "Our operatives and the hunters had been combing the bushes and forests for the past one week," she said. Opalola said the kidnappers had to abandon their captives when security forces closed in on them. She said the foreigners became ill while in captivity and were being given medical care. "We met them in a terrible state. These were people who were made to endure rough weather and not properly fed in captivity," she said. She said no arrests had been made. Kidnapping for ransom used to be common in Nigeria's oil-producing south but has lately spread to other parts of the country. The victims are usually released after a ransom is paid although police rarely confirm if money changes hands. Chinese firms are working in Nigeria on multi-billion-dollar infrastructure projects that include mining, railways, airports and roads. Their workers have been repeatedly targeted by kidnap gangs. Last July, four Chinese workers were abducted from a quarry site in southern Cross River state while their police guard was killed. They were released one month later. joa/pma/mjs