Counting will resume for Nigeria's election with the two main presidential candidates in close contention. The US and Britain have expressed concern over possible political interference in the tally.
Counting stopped just before midnight on Monday with incumbent President Goodluck Jonathan winning ten states and the small Federal Capital Territory while opposition candidate Muhamadu Buhari took nine states.
But Buhari had won many more votes, 8.5 million to Jonathan's 6.48 million.
When final counting resumes on Tuesday morning, a further 18 states will send in results to the counting center in Abuja. They include Lagos, which has the largest number of voters in any of the states. The count in Abuja is being carried out in the presence of party representatives, national and international observers and media.
In only the eighth election since independence from Britain in 1960, it is the first time a challenger has a realistic chance of defeating the president.
As expected, the 72-year old Buhari, a Muslim from the north region that is home to farmers and cattle herders, won the northern states of Kano and Kaduna, but his margin of victory was impressive. In Kano, the state with the second-largest number of voters, Buhari won 1.9 million votes to Jonathan's 216,000. In Kaduna, Buhari won 1.1 million votes to Jonathan's 484,000.
Parliamentary elections are also being held and the opposition, as of Monday's results, was slightly ahead of Jonathan's party in the House of Assembly. Voting for 13 constituencies was postponed until April because of a shortage of ballot papers.
The 57-year old Jonathan is a Christian from a minority tribe in the oil-producing south of the country. His five-year term has been marked by allegations of corruption and the ongoing insurgency in the north of the country by the Boko Haram terror group.
US and UK voice concerns
On Monday, the US and British governments voiced concern about possible political interference in the final tallying of the results.
"So far, we have seen no evidence of systemic manipulation of the process," US Secretary of State John Kerry and British Foreign Secretary Philip Hammond said in a joint statement.
"But there are disturbing indications that the collation process, where the votes are finally counted, may be subject to deliberate political interference," they added.
Jonathan's party called the suggestions "absolute balderdash" and demanded evidence.
In Rivers state, home to Africa's biggest oil and gas industry, Jonathan was reported to have won 95 percent of the vote.
jm/bk (Reuters, AP)