PORT HARCOURT, Nigeria - Gunmen have seized seven hostages from an Italian oil supply vessel off the coast of southern Nigeria, police and company officials said Wednesday.

Nigerian soldiers on patrol in the oil rich Niger Delta region in a file photo. Gunmen in speed boats kidnapped several workers including a number of foreigners in a raid on an Italian oil production vessel off the Nigerian coast on Wednesday, industry and security sources said. [Reuters]

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Twenty-five foreign workers and nearly 60 Nigerian employees were aboard a vessel belonging to a subsidiary of Italian oil giant Eni SpA that was attacked overnight, Eni said in a statement.

The company said 10 armed men attacked the ship and took seven people away on a speedboat. One of the hostages was an Italian worker at Saipem, an Eni subdivision. The company did not give the nationalities of the other hostages.

Nearly all those on the vessel were held at gunpoint for a period before the attackers left with the seven captives, a private security contractor said, speaking on condition of anonymity because he was not authorized to talk to the press.

The ship was not damaged and those who remained on board were reported in good condition, Eni said.

Eni said it was in contact with the Italian Foreign Ministry and local authorities in Nigeria.

Police spokeswoman Irejua Barasua confirmed that an attack occurred on an oil vessel, but did not provide further details.

The vessel was about 30 miles off the coast of Nigeria's Rivers State at the time, the contractors said.

Another oil security worker said a ransom demand had already been received by the company.

The kidnappings were the latest in a series of attacks on oil installations in the volatile Niger Delta, where most of Nigeria's oil is produced.

Most oil workers kidnapped in the past year have been safely released. The captives are usually freed after a ransom is paid by the companies and the government, according to security analysts.

Since the beginning of this year, militant groups have attacked oil pipelines and taken workers hostage in violence that has cut about 25 percent of Nigeria's usual crude output of about 2.5 million barrels daily. Civilian protesters have also taken over oil facilities to protest lack of jobs and development in the regions.

On Monday, Eni said a two-week armed siege at its Tebidada oil pumping station in Nigeria ended peacefully and the company resumed an output of 50,000 barrels per day. The facility, located in Bayelsa state, had been occupied Nov. 6 by a group of militants and villagers who took 48 Nigerian staff members hostage, seeking compensation from the company for oil spills. Several hostages escaped and some were released.

Despite Nigeria's being Africa's biggest oil producer, most inhabitants of the oil-rich delta remain poor. The country is the world's eighth-biggest oil exporter and the fifth-largest source of U.S. oil imports.