Washington, April 2 (IANS): US President Barack Obama on Wednesday pledged continuing US support to Nigeria and its regional partners in the fight against extremist group Boko Haram, a media report said on Thursday.

In a separate telephonic talks with Nigerian President Goodluck Jonathan and president-elect Muhammadu Buhari, Obama highlighted the need for Nigeria and its regional partners to build on the recent progress against Boko Haram, the White House said in a statement, Xinhua reported.

Obama encouraged both leaders to work together to unify the country and sustain Nigeria's strong partnership with the United States to tackle the critical challenges facing Nigeria and the broader region, said the statement.

Buhari, candidate of Nigeria's opposition All Progressives Congress, was officially declared president-elect on Wednesday, the first time that a sitting president has been defeated in the polls since the country gained independence from Britain in 1960.

Obama congratulated Buhari on his victory and thanked him for repeatedly urging his supporters to help ensure that the election process remained calm and peaceful.