U.N. Secretary General Ban Ki-moon is to arrive in Nigeria Sunday to commemorate the Boko Haram bombing of his organization's headquarters and focus new attention on 219 schoolgirls held by the extremists.

Ban is to meet with Nigeria's new President Muhammadu Buhari on Monday, amid plans to launch a long-delayed regional offensive against Nigeria's Islamic insurgents.

A U.N. statement says the leaders will discuss ways to counter violent extremism as well as human rights and climate change.

Ban also will meet the Bring Back Our Girls group which demands government action to free 219 abducted schoolgirls held now for nearly 500 days.

He will lay a wreath to mark the anniversary of the Aug. 26, 2011 suicide car bombing that killed 21 people at the U.N. Nigeria headquarters in Abuja.