Seven contractors, including three Australians and a South African, have been released unharmed four days after they were kidnapped by gunmen in southern Nigeria, local police and a state security adviser said, yesterday.

Police had earlier given accounts of how many had been seized and what their nationalities were, and that they all worked for cement company Lafarge on the outskirts of Calabar, Cross River State, in the Niger Delta.

Cross River State Commissioner, Jimoh Ozi-Obeh, said they were released “unhurt” yesterday,  but gave no further details.

The state governor’s security adviser, Jude Ngajim said five expatriates and two Nigerians had been released.

“They are safe and sound,” he said, noting that a doctor had made medical checks and pronounced them “fit and sound.”

Kidnappings of foreigners are common in the region, which holds most of the Organisation Producing Exporting Countries, OPEC,   member’s crude oil and contributes about 70 per cent of national income.

Nigeria has remained Africa’s top oil producer until a recent spate of attacks on oil facilities.