The Nigerian Air Force said it had killed a number of senior Boko Haram fighters and possibly their overall leader, as U.S. Secretary of State John Kerry arrived for talks on tackling the militants.

Government planes attacked the Islamist group inside the Sambisa forest in its northeast heartland Friday night, the air force said Tuesday, saying it had only just confirmed details of the raid.

"Their leader, so called 'Abubakar Shekau,' is believed to be fatally wounded on his shoulders," the statement by military spokesman Col. Sani Kukasheka Usman added, without going into details on the source of its information.