An investigation has alleged that the Nigerian government paid a substantial ransom to secure the release of up to 230 children and staff abducted from a Catholic boarding school in November. The pupils were taken from St Mary’s in Niger state during a mass kidnapping by Boko Haram. Intelligence sources told AFP that millions of dollars were delivered by helicopter to militants in northeastern Borno state after negotiations reportedly led by national security adviser Nuhu Ribadu. Two Boko Haram commanders were also said to have been freed. Officials publicly denied paying any ransom, insisting that government agents do not negotiate with kidnappers. The Islamist insurgent group, active since 2009, has carried out widespread violence and abductions across northern Nigeria. Reports suggest the children were released in stages after confirmation that the payment had been received.