Three kidnapped Chinese technicians were freed on early Saturday morning in the Niger Delta region of Nigeria, an official from the Chinese Consulate General in Lagos said.

The three male technicians, who worked for a Nigerian steel company,were kidnapped at 11 a.m. local time (1000 GMT) on May 23 in Aba City, Abia state in southeast Nigeria, by unknown armed people. Other nine Nigerians were also abducted in the incident.

They were freed at about 6 a.m. local time (0500 GMT) on Saturday, the official said on condition of anonymity.

They are in good condition and are expected to return to China soon, he said.

The oil-rich Niger Delta of Nigeria has been restive for years with militants attacking both foreign oil facilities and workers.

Over 300 foreigners have been seized in the Niger Delta since 2006. Almost all have been released unharmed after paying a ransom.

The Chinese Consulate General in Lagos has asked Chinese citizens in Nigeria to be alert of the security situation. It advised Chinese not to go to the southeast part of Nigeria, like Abia state.

The development came almost one week after a local police spokesperson told Xinhua last Saturday that four kidnapped Lebanese workers of a construction company in southern Nigeria have been released by their abductors.

The Lebanese were kidnapped by gunmen dressed like soldiers on May 14 in the oil-rich Delta region.