"Following the postponement of general elections in Nigeria to 28 March and 11 April, the Secretary-General strongly urges the Government and the Independent National Electoral Commission (INEC) to ensure these new dates are maintained, in accordance with the provisions of the Nigerian Constitution," the UN said in a statement published Friday on its website.
Ban Ki-moon also expressed strong concern over reports of election-related violence.
The Boko Haram extremist group began large-scale attacks in 2009 in northeast Nigeria, with the aim of establishing an Islamic state with strict Sharia law.
Since then, the group killed over 5,000 and displaced more than 300,000 people, according to US-based think tank Council on Foreign Relations.
In February, the group expanded its attacks from Nigeria to neighboring Niger, Cameroon and Chad.