One person died and dozens were injured during a stampede at President Paul Kagame's campaign rally, Rwanda's national broadcaster reported, ahead of a vote widely expected to extend the incumbent's 24-year iron-fisted rule.

Kagame has been Rwanda's de facto ruler since the end of the 1994 genocide which claimed some 800,000 lives, mostly Tutsis but also moderate Hutus.

President since 2000, the 66-year-old will face the same rivals as he did in 2017: the leader of the opposition Democratic Green Party, Frank Habineza, and former journalist, Philippe Mpayimana, who is running as an independent.

Campaigning kicked off on Saturday, with Kagame addressing rallies in Musanze and Rubavu in northern Rwanda on the weekend.

"One person died and 37 others were injured in a stampede that occurred during the RPF-Inkotanyi campaigns in Rubavu on Sunday," the state-run Rwanda Broadcasting Agency reported, using the official name for Kagame's party.

"The Ministry of Local Government asked those participating in the campaign to follow the instructions and regulations aimed at ensuring safety and security," the broadcaster added.

Rwandan courts rejected appeals from prominent opposition figures Bernard Ntaganda and Victoire Ingabire to remove previous convictions that effectively barred them from contesting.

The election commission also barred Kagame critic Diane Rwigara, saying she had failed to provide a criminal record statement as required, and had not met the threshold of acquiring 600 supporting signatures from citizens.

Elected by parliament in 2000 after the resignation of former president Pasteur Bizimungu, Kagame has won three elections with more than 90 percent of the ballot in 2003, 2010 and 2017, taking nearly 99 percent of votes in the most recent poll.

He has been praised for Rwanda's economic recovery after the genocide but faces criticism over rights abuses and political repression.