Technical failures at polling places have caused disruptions, and the opposition has warned of government vote rigging amid an internet blackout.

When Yoweri Museveni seized power in Uganda in 1986, he said "the problem of Africa in general and Uganda in particular is not the people but leaders who want to overstay in power."

Ugandans are voting in a tense presidential election as 81-year-old President Yoweri Museveni seeks to extend his four-decade rule amid an internet shutdown and heavy military deployment.

President Yoweri Museveni and his political opponents in Uganda held their final rallies on Tuesday ahead of an election that authorities will oversee with soldiers in the streets, deployments that have alarmed opposition figures who see signs of the authoritarianism they want to oust.

Millions of Ugandans will Thursday cast their votes in a crucial presidential rematch between a former pop star and their long-time authoritarian leader, who aims to prolong his nearly 40-year rule.

Analysts say President Yoweri Museveni will almost certainly stay in power, despite the challenge from musician-turned-politician Bobi Wine.

Ugandans go to the polls tomorrow in an election where President Yoweri Museveni is widely expected to be reelected, as authorities crack down on political dissent.