Early results from Nigeria's presidential election show incumbent Muhammahu Buhari in the lead, but the main opposition party is rejecting the vote counts, calling them "incorrect and unacceptable."
Nigeria's Independent National Electoral Commission (INEC) said Monday Buhari had won the vote in at least six states, with main challenger Atiku Abubakar winning in the Federal Capital Territory.
The chairman of Abubakar's People's Democratic Party, Uche Secondus, said the party has discovered "irregularities" in Nasarawa state and the capital.
Speaking at a news conference in Abuja, he alleged the Buhari administration has colluded with INEC to manipulate results from polling units across the country. Secondus said the PDP has what he called the "original results" from polling stations around the country.
Voting took place Saturday in all of Nigeria's 36 states and the federal capital territory, although INEC postponed the polls in some areas where voting was disrupted.
The Situation Room, an umbrella group of more than 70 civil society organizations, says at least 39 people had been killed in election-related violence.
Despite the rescheduling of some elections, INEC said it was "generally satisfied" with the vote, the French news agency reported.
In a statement Monday, U.S. Ambassador Stuart Symington called on Nigerians to be patient and refrain from violence as INEC compiles and announces the results.
"No one should break the law by announcing results before INEC does, or break the peace by claiming victory before the results are final," Symington said.
Political tensions were high last week as Nigerians prepared to elect a new president and parliament. During the campaign, Buhari's All Progressives Congress and the People's Democratic Party accused each other of attempting to fix the outcome.
Last week, Buhari urged the military to be "ruthless" with anyone who tries to interfere in the voting process. The remark drew sharp criticism from Abubakar, who said the military has "no role to play" in the elections.
Nigeria's elections were initially planned for February 16 but the electoral commission, citing logistical issues, abruptly postponed them just five hours before polling stations were set to open.
After ruling briefly as a military dictator in the 1980s, Buhari won the 2015 election, becoming the first opposition candidate to defeat a sitting president.