Five Chinese telecommunications workers and an Italian oil worker abducted in Nigeria's restive southern delta region have been released, militants and officials said Thursday.

A rebel group that has carried out crippling assaults against the energy industry in Africa's oil producer announced the Italian's release in an e-mail and identified him as Roberto Dieghi.

He was among three Italians and one Lebanese man seized in a Dec. 7 raid on an oil export terminal operated by Agip, a subsidiary of Italian oil firm Eni SpA. The two other Italians and the Lebanese remained in custody, the militant Movement for the Emancipation of the Niger Delta said.

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

Eni confirmed Dieghi's release in a brief statement on its Web site that gave no details of his condition.

Complete coverage is available in FOXNews.com's Africa Center.

Separately, Nigerian government officials and China's Foreign Ministry said five kidnapped Chinese telecommunications workers were freed Wednesday night by their captors. The militant group has denied responsibility for their abduction.

The Chinese workers were abducted Jan. 5 from their residence in a village outside Port Harcourt in the oil-rich Niger Delta.

"We want to express our thanks and support for the assistance on the Nigerian side," ministry spokesman Liu Jianchao told reporters at a regularly scheduled news conference.

In a brief statement on its Web site, the Foreign Ministry said its diplomats and officials from China's Commerce Ministry had worked with the Nigerian government to secure the workers' release.

"All have been safely rescued," the statement said without providing details on how they were released. A Rivers state government official, Emeke Woke, said the Chinese were handed over to their company's lawyers in that state.

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

Some 80 foreign oil workers were seized last year. Kidnappings generally end peacefully. One Briton, however, died in a gunfight between his militant captors and Nigerian government forces.

On Tuesday, 16 gunmen aboard 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.

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.

Attacks on the country's oil industry since early 2006 have cut exports by 25 percent. Nigeria, which is preparing for presidential elections in April, used to produce 2.5 million barrels of oil per day.

The militants also announced a change in tactics, saying they would halt kidnappings and concentrate instead on "acts of sabotage, including bombings, aimed at crippling the oil sector."

Get complete coverage in FOXNews.com's Africa Center.