A file photo of an anti-riot police officer leaving the scene of a disturbance in Nigeria. Picture: Pius Utomi Ekpei

Prime Minister Malcolm Turnbull confirmed the men, who are believed to have been working for Perth-based mining company Macmahon Holdings, had been captured near Calabar in Nigeria’s south.

The families of those taken have been notified and the Australian high commissioner is at the scene, he said.

“We don’t know at this stage the identity of the kidnappers,” Mr Turnbull told reporters while campaigning in Geelong.

Mr Turnbull said three of the kidnapped men were Australian and the fourth a NZ citizen who had Australian residency.

Their local driver was killed during the attack on the group’s vehicle. Another Nigerian and one South African were also reportedly kidnapped.

“It is a very serious kidnapping,” Mr Turnbull said.

The men were contractors for cement company Lafarge Africa and were attacked around 5.30am local time on Wednesday, police said. Lafarge Africa said it was informed of the incident by Macmahon, which carries out quarrying operations at the UniCems joint venture cement plant in Mfamosing near Calabar.

Macmahon Holdings has put its shares in a trading halt on the Australian Securities Exchange ahead of an expected announcement about the kidnapping.

Foreign Minister Julie Bishop said the government was in close contact with the Nigerian government, which is taking the matter extremely seriously.

“I have spoken with our ambassador in Nigeria this morning. I have also spoken with the heads of MacMahon, the mining firm affected by this,” she told media Thursday morning.

“I can confirm that seven people were ambushed and abducted. Three Australians and an Australian permanent resident who was a national of New Zealand, one One Australian was able to avoid the kidnap. Tragically, one Nigerian, a driver was killed and we extend our sympathies to the families.

Ms Bishop said her department was working closely with Nigerian authorities.

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 longstanding 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.

— With AFP