Ugandan President Yoweri Museveni looks set to extend his 30 years in power with official results showing him taking a strong lead in elections.
With more than 80% of the ballots counted, Mr Museveni has secured 61% of the votes.
His main rival Kizza Besigye, who is under house arrest, is on 34%. Full results are due in a few hours’ time.
The election has been marred by sporadic violence and opposition allegations of electoral fraud.
Social media sites and messaging apps have also been blocked.
Mr Besigye was arrested on Friday on suspicion he was planning to publish his own results, breaking electoral laws, police said, before being escorted to his home.
“We shall detain him until results are announced,” Kampala police chief Andrew Felix Kaweesi told Uganda’s New Vision newspaper.
It is the fourth time Mr Besigye, candidate for the opposition Forum for Democratic Change, has taken on President Museveni.
The two men were once allies, with Mr Besigye serving as Mr Museveni as his personal doctor when they were guerrilla fighters.
Mr Museveni seized power in 1986 and although is credited with restoring stability to Uganda. However, critics say he has become increasingly authoritarian.