Supporters of incumbent Ugandan President Yoweri Museveni celebrate in the streets of Kampala on Saturday. Photo: AFP

Uganda's Yoweri Museveni has won a sixth term in office, the election commission said Saturday, extending his 35-year rule.

The 76-year-old leader, who took power in 1986, is one of Africa's longest-serving presidents. 

Museveni won with 58.6 percent of the vote, seeing off a stiff battle from 38-year-old former ragga singer Bobi Wine, who fired up a youthful population where three quarters are under 30 years old.

Wine was under heavy guard at his home on the outskirts of Kampala as the results were announced. 

The singer-turned-MP was among 10 opposition candidates and came second with 34.8 percent of the vote.

"The electoral commission declares Yoweri Museveni... elected President of the Republic of Uganda," said election commission chairman Justice Simon Mugenyi Byabakama.

He said turnout was 57.22 of almost 18 million registered voters.

Security forces poured into the streets of Kampala after the announcement, with one soldier atop an armored personnel carrier urging citizens to maintain social distancing as a helicopter buzzed overhead.

Images on state television showed jubilant Museveni supporters in his home district waving flags and cheering, while soldiers in the capital helped marshal motorcycle drivers for a parade - handing them yellow vests and Museveni ­posters.

Museveni, in a wide-ranging speech on state television after the announcement, thanked his supporters and said that now, "the only thing to avoid is violence."

"I think this might turn out to be the most cheating-free election since 1962," when the country achieved independence, he said.