LAGOS, Nigeria - Militants in Nigeria said Thursday they released one of three Italian hostages seized last month in an attack in the country's oil-rich southern delta region.

The militant Movement for the Emancipation of the Niger Delta, which has launched crippling attacks against the energy industry in Africa's oil giant since last year, announced the release in an e-mailed statement and identified the freed hostage as Roberto Dieghi.

Three Italians and one Lebanese man were seized in the Dec. 7 raid on an oil export terminal operated by Agip, a subsidiary of Italian oil firm Eni SpA.

The militant group had said Wednesday it was negotiating over the men's release with the local Bayelsa State government.

The statement said the release "had absolutely nothing to do with Roberto Dieghi's poor state of health. The release of Mr. Dieghi is an act of goodwill on our part which we hope will be reciprocated by the Nigerian government."

Dieghi was handed over to the government delegation, the statement said. It was not immediately possible to verify the claim and there was no word on Dieghi's condition.

"There are no discussions on going about the release of the remaining two Italians and one Lebanese still in our custody. They are being held indefinitely," the statement said.

More than a year of stepped-up violence in the impoverished region of creeks and swamps has cut nearly one-fourth of Nigeria's usual 2.5 million-barrel crude production, helping to send global oil prices soaring.

Amid the bombings of oil and military installations, some 80 foreign oil workers were seized last year. Kidnappings generally end peacefully with the hostages released after a ransom is paid. One Briton, however, died in a gunfight between his militant captors and Nigerian government forces.

As political jockeying starts ahead of general elections in April, there has been violence in the Niger Delta region unclaimed by the main militant group. Winners in Nigeria's notoriously corrupt political arena control oil revenues apportioned by the federal government. Much of the oil funds are stolen.

On Tuesday, 16 gunmen on two boats approached a vessel carrying 10 oil workers, including those from South Korea's Hyundai Heavy Industries Co., South Korea's Foreign Ministry said in a statement.

A Dutch national and two Nigerians were killed and five others, including the South Korean worker, were wounded in the attack as they traveled from Port Harcourt to Bonny Island in the southern delta, it added. The gunmen removed goods from the boat after the attack.

It was unclear who opened fire first.

The Dutch victim and one of the Nigerians died Tuesday. Rivers State police spokeswoman Irejua Barasua said the other Nigerian died Wednesday of wounds suffered in the attack.

Hyundai Heavy Industries is building an oil refinery in Nigeria.

Despite producing tens of billions of dollars in oil revenue every year, the delta region remains deeply impoverished. Attacks on foreign workers by robbers, kidnappers and militants demanding a share of the country's oil wealth are common.