The employees of Italian oil contractor Saipem were abducted at gunpoint by members of a community in the oil capital, Port Harcourt, where Saipem was working and which was in dispute with the company over compensation for environmental damage in the oil capital, Port Harcourt.
Rivers State Police Commissioner, Samuel Agbetuyi, told Reuters by telephone on Friday that:"They have been released. The issues of disagreement must have been resolved."
A Bukuma community leader, Mbaka Harmony, told a local radio station that the community was demanding 300 million naira ($2.3 million) in compensation for damage caused by Saipem's laying of a pipeline through the area.
In Rome, the Italian foreign ministry confirmed the release of the Italian national, Vito Macrina, and the two other men.
The kidnapping was unrelated to a five-month campaign of sabotage, bombings and kidnapping against Nigeria's Western-run oil industry by militants fighting for more economic autonomy in Nigeria's far south.
The attacks by the Movement for the Emancipation of the Niger Delta (MEND) have reduced Nigerian oil exports by a quarter since February.
MEND rebels have cut Nigeria's oil
output (file photo)
The latest abduction, and the killing of a US oil executive in Port Harcourt on Wednesday, marked a new low in security in the world's eighth-largest oil exporter.
Kidnapping is a fairly common method used by poor villagers in the lawless delta, suffering neglect by their own government, to extract benefits or cash from oil companies.
Hostages are routinely released after payment of a ransom, although some oil companies have banned such payments.
Port Harcourt is the largest city in the Niger Delta, which produces all of Nigeria's oil, and several multinationals have major offices there, including Royal Dutch Shell and Agip.
Militancy is fuelled by resentment among many delta inhabitants, who feel cheated out of the riches being produced from their tribal lands.
Neglect and corruption have eroded trust in government, while communal rivalries and abuses by the military have led to the rise of well-armed community militias.
MEND's emergence in December has raised the stakes in the delta, because it introduced more professional guerrilla tactics, more deadly firepower and a clearer political dimension to the violence.