Port Harcourt - Nigerian police on Wednesday said three foreign nationals, two Australians and a South African and two Nigerians were kidnapped in the country's southeast after their vehicle was attacked.
The hold-up, in which the driver was also shot dead, happened in the Akpabuyo district near the capital of Cross River state, Calabar, at about 7 am (0600 GMT) on Wednesday.
All five were workers with Australian mining and engineering giant Macmahon, which was contracted to cement major LafargeHolcim in the state, police commissioner Jimoh Ozi-Obeh told reporters.
"The police is currently working with the Nigerian Navy to ensure that the victims are released unharmed," he added.
"The police is aware of the matter. Five persons were kidnapped. They include two Australians, one South African and two Nigerians. The driver of the vehicle was shot dead."
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The commissioner said no ransom demand had been received.
One witness to the abduction, who asked not to be identified, said the kidnappers took the men to a waiting boat.
LafargeHolcim spokeswoman Viola Graham-Douglas said the company was informed of the incident by Macmahon, which was "working with the security agencies to resolve the situation".
Macmahon has an $18 million per year contract with the United Cement Company of Nigeria Ltd (UniCem) for quarrying operations at UniCem's cement manufacturing plant at Mfamosing, near Calabar.
UniCem is a joint venture between Franco-Swiss conglomerate LafargeHolcim and Flour Mills of Nigeria, according to the Australian firm's website.
Kidnapping for ransom has been a long-standing problem in southern Nigeria, particularly in the oil-producing delta region, where criminal gangs target wealthy Nigerians and expatriate workers.
Most are usually released after the payment of a ransom.