Uganda's President Yoweri Museveni has taken a strong lead in partial results from Thursday's presidential election, the electoral commission says.

Figures announced on Friday morning put Museveni in front with 76% of the votes, based on returns from 45% of the country's polling stations.

He is followed by opposition leader Bobi Wine with about 20%.

Ugandans voted in a tense national election on Thursday after an often violent campaign, with President Museveni, 81, seeking a seventh term in office.

Wine, a 43-year-old pop star-turned-politician, has alleged "massive" fraud during the election, which was held under an internet blackout. He did not provide documentary proof and the authorities have not responded to his allegations.

Late on Thursday, Wine's National Unity Platform (NUP) party said that the military and police had surrounded his house in the capital, Kampala, "effectively placing him and his wife under house arrest".

"Security officers have unlawfully jumped over the perimeter fence and are now erecting tents within his compound," the party posted on X. The authorities are yet to comment.

Following the 2021 election, in which he garnered 35% of the vote, Wine was confined to his home for several days by security forces.

During Thursday's vote, voting was delayed by up to four hours in many polling stations around the country as ballot boxes were slow to arrive and biometric machines, used to verify voters' identity, did not work properly.

Some have linked the problems to the network outage.

Although there are other six candidates, the presidential poll is essentially a two-horse race between Museveni and Wine, but given the president has won the six previous elections, analysts say he is likely to further extend his time in power.

Wine, who says he represents the youth in a country where most of the population is aged under 30, has promised to tackle corruption and impose sweeping reforms, while Museveni argues he is the sole guarantor of stability and progress in the country.

The campaign period was marred by the disruption of opposition activities - security forces have been accused of assaulting and detaining Wine's supporters.

Police spokesperson Kituuma Rusoke dismissed these complaints, accusing opposition supporters of being disruptive.

Internet access was suspended on Tuesday, with Uganda's Communications Commission saying the blackout was necessary to prevent misinformation, fraud and the incitement of violence - a move condemned by the UN human rights office as "deeply worrying".

Wine, whose real name is Robert Kyagulanyi, had called on his supporters to protest, if Thursday's election results were manipulated.

However, as of Friday morning, there have been no signs of any demonstrations.

A Museveni victory would extend the former rebel leader's four-decade grip on power. He is widely believed to favour his son, military chief Muhoozi Kainerugaba, as his successor, though he denies grooming him for the role.

The final presidential result is expected be announced by 16:00 local time (13:00 GMT) on Saturday, according to the electoral commission.

Additional reporting by Sammy Awami in Kampala