The UN Security Council has said it is alarmed by ties between Nigeria’s Boko Haram Islamist militants and the Islamic State (IS) group.
In a statement, it said Boko Haram – which pledged allegiance to IS in 2015 – continued to “undermine the peace and stability” in West and Central Africa.
Meanwhile, a senior US official said there were reports of Boko Haram fighters joining IS in Libya.
Nigeria is to host a summit on Saturday on fighting Boko Haram.
President Muhammadu Buhari will welcome counterparts from Benin, Cameroon, Chad and Niger for the gathering in Abuja, along with French President Francois Hollande, UK Foreign Secretary Philip Hammond and US Deputy Secretary of State Antony Blinken.