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.

Nigeria's military said Sunday that it killed 20 Boko Haram Islamists while repelling an attack by the extremist group in the embattled northeastern state of Borno. "Boko Haram terrorists attempted to attack a military barracks (in Borno) at about 5:00 am (0400 GMT)," spokesman Lieutenant Colonel Sagir Musa said in a statement. He said the attack occurred in the village of Monguno, about 200 kilometres (124 miles) from Borno's restive capital of Maiduguri, considered Boko Haram's home base where the radical group has been blamed for scores of deadly attacks.

Nigerian Vice President Namadi Sambo said Saturday that his government is ready to consider a ceasefire offer by the extremist Islamist group Boko Haram. Sambo, speaking during a visit to the northeastern city of Maiduguri -- the Islamists' stronghold -- said "we welcome the ceasefire offer announced recently by the Boko Haram group and we will do everything as a government to see that we achieve a lasting peace in Nigeria." Since 2009, violence linked to Boko Haram's insurgency has claimed some 3,000 lives, including killings by the security forces.