Ugandan President Yoweri Museveni has won a fifth term as president, extending his 30 years in office.
The 71-year-old won 60.75% of the vote while his nearest rival Kizza Besigye took 35%, the election commission said.
Mr Museveni’s supporters said his opponents had failed to offer any chance of progress.
But Mr Besigye, who is under house arrest, said the results were a “sham”, calling on the international community to reject them.
“We have just witnessed what must be the most fraudulent electoral process in Uganda,” he said in a statement.
EU observers have also criticised the poll, saying the governing party had created an “intimidating atmosphere” and that the opposition alleged vote rigging.
While praising the “remarkable determination” of Ugandans to vote, EU Chief Observer Eduard Kukan said the governing National Resistance Movement’s “domination of the political landscape distorted the fairness of the campaign”.
The election has been marred by sporadic violence and opposition allegations of electoral fraud, with social media sites and messaging apps blocked.
Mr Besigye was put under house arrest on Friday on the suspicion he would announce the results himself, breaking electoral laws, police said.
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 is credited with restoring stability to Uganda. However, critics say he has become increasingly authoritarian.
The next closest challenger to Mr Museveni, former Prime Minister Amama Mbabazi, is also reportedly under house arrest.
- Kizza Besigye, 59, a veteran opposition leader. He has lost the last three elections
- Amama Mbabazi, 67, former ally of President Museveni and once prime minister – also served as defence, security and justice ministers
- Yoweri Museveni, 71, in power since winning a five-year guerrilla war in 1986 – one of Africa’s longest-serving leaders. His final term was meant to end in 2006, but in 2005 he won a campaign to lift the constitutional term limits