A former Nigerian oil minister who was kidnapped at the weekend by gunmen in the northeastern city of Maiduguri, a stronghold of Islamist group Boko Haram, was released on Monday, police said.
"I can confirm that Shettima Ali Monguno has been released today by his abductors," Borno State police chief Abdullahi Yuguda told AFP.
A security source who requested anonymity said the kidnappers were paid 50 million naira ($318,000, 242,766 euros), but the police chief declined to comment on the circumstances surrounding the release.
The ex-minister's son, Abubakar Ali Monguno, had told AFP that the kidnappers demanded a ransom hours after the Friday abduction outside a mosque in Maiduguri.
No group has claimed the abduction, but analysts have said that Boko Haram has increasingly turned to ransom payments to finance its insurgency, notably by kidnapping wealthy individuals around Maiduguri.
Criminal groups have also carried out attacks under the guise of Boko Haram.
Monguno, 87, served as Nigeria's oil minister in the 1970s and held the rotating presidency of the Organisation of the Petroleum Exporting Countries (OPEC) in 1972.
He was among a group of elders who met President Goodluck Jonathan in Maiduguri in March to discuss the Boko Haram crisis.
He has repeatedly called for dialogue with the militant group and urged Jonathan to reduce the massive security deployment in the city and ease a curfew forcing all residents to stay indoors after sundown.