Concerns over violence spark top US diplomat Kerry to visit Nigeria's presidential candidates

U.S. Secretary of State John Kerry's plan to stop in Nigeria for meetings with the two leading candidates in the upcoming presidential election signals deep U.S. concerns about postelection violence in a country already devastated by an al-Qaida-linked insurgency.

No chief American diplomat has visited Nigeria since 2012. Kerry's expected stopover in Lagos for a few hours Sunday overrides policy that senior American officials stay away from countries about to hold elections, to avoid the perception of favoring one candidate over another.

State Department officials say Kerry is to hold separate talks with Nigeria's president and his leading opponent, a former Army general. The secretary of state previously has paid pre-election visits to countries including Lebanon in 2009 and Iraq in 2005.