By Felix Onuah
ABUJA (Reuters) - U.N. Secretary-General Ban Ki-moon pledged support on Monday for Nigeria's efforts to counter Boko Haram and tackle the causes of militancy in the country's northeast, where he described humanitarian conditions as particularly worrying.
Ban also pledged to strengthen democracy in Nigeria after a peaceful election brought President Muhammadu Buhari to power in March. It was the first democratic transfer of power in Africa's most populous nation.
"I hope that this example will be emulated by many countries around the world ... I want to commend the people of Nigeria on the peaceful, free and fair elections," Ban said in Abuja after meeting Buhari.
He said the two men discussed security and development issues "including the cause of troubling levels of violence and terror perpetuated by Boko Haram in northeastern Nigeria and beyond".
The United Nations would also work with Nigeria "to address and counter extremism and terrorism", he added, reiterating calls for the unconditional release of over 200 Chibok schoolgirls abducted by Boko Haram 500 days ago.
"The humanitarian situation in the northeast is particularly worrying. We are working with partners on the ground to scale up humanitarian operations," he said.
Ban also commemorated the fourth anniversary of the bombing of the U.N. headquarters in Abuja, which killed 23 people, in an attack claimed by Boko Haram.
Boko Haram has waged a deadly campaign to carve out a state adhering to strict Islamic law in Nigeria's northeast for the past six years. After being pushed out of most of the territory they gained earlier this year, the group scattered and returned to attacking soft targets.
(Writing by Chijioke Ohuocha; Editing by Dominic Evans)