The Nigerian military is accused of killing dozens of young men in a northern city in an apparent search for members of the extremist group Boko Haram.
Any future Nigerian president would serve only a single term but it may be extended by two years under a proposal from Nigeria's current leader.
April presidential elections in Nigeria may have been the fairest in years but they were also the bloodiest, Human Right Watch said Monday from Senegal.
The results of the Nigerian presidential election that gave a full term to Goodluck Jonathan last month were "manipulated," an opposition leader said.
What was supposed to be the third and final round of voting got under way in Nigeria Tuesday as citizens went to the polls to cast ballots for state governors.
A defeated candidate in Nigeria's election maintains his supporters weren't allowed to vote in some regions while urging calm following violence in the north.
Rioting in northern Nigeria after the election of President Goodluck Jonathan has left "many dead" and displaced about 16,000 people, the Red Cross said.
Riots broke out across northern Nigeria Monday after incumbent Goodluck Jonathan claimed victory in the presidential election, authorities said.
Election workers in Nigeria were counting ballots Sunday and said it appears to have been a close presidential race.
A former candidate for Nigeria's presidency has filed an additional 20 appeals calling for an investigation into last year's election, but to no avail.