Malians started voting in a run-off election, with Ibrahim Boubacar Keita set to beat the opposition despite a surge in violence during his tenure. Picture: Reuters/Luc Gnago

Bamako - Malians started voting in a run-off presidential election on Sunday, with incumbent Ibrahim Boubacar Keita expected to beat the opposition challenger despite a surge in ethnic and militant violence during his tenure.

The first round on July 29 was marred by armed attacks and other security incidents at about a fifth of polling places. The threat of violence could dampen turnout on Sunday but as voting got underway, no serious incidents were reported.

The chaotic first round was a reminder that militants, some linked to al Qaeda and Islamic State, have regrouped since a French intervention in 2013 and are now expanding their influence across Mali's desert north and into the fertile centre.

Dramane Camara, 31, was the first to vote at one polling station in a school in the capital Bamako.

"I voted without problem, I came to fulfill my duty as a citizen," Camara said. "I expect the new president to solve the problem of the North, which is peace. Because the return of peace means the return of NGOs, investors, so creating jobs."

Keita took 41 percent of the vote in last month's first round against nearly 18 percent for Soumalia Cisse, a former finance minister and the main opposition leader.

Cisse subsequently accused Keita's government of voting fraud but the constitutional court upheld the result.

Cisse, 68, blames Keita, 73, for the worsening violence and accuses his government of rampant corruption.

"Continuing on the path followed by those who had the heavy responsibility to preside over the destiny of our country would lead us closer to chaos and the abyss," Cisse warned at his final campaign rally on Friday.

Civil society website Malilink recorded 932 militant attacks in the first half of 2018, almost double that for all of 2017. Their activities in Mali and its Sahel neighbours have unnerved Western powers like France and the United States who have deployed thousands of troops across the region.

Jihadists are also stoking inter-communal conflict, mostly between herders and pastoralists. Killings along ethnic lines have claimed hundreds of civilian lives this year, including at least 11 last week in the central Mopti region.

Keita's better-than-expected first-round showing and Cisse's failure to win endorsements from the third and fourth-place finishers augur well for the incumbent. Keita beat Cisse in a 2013 run-off and is seeking a second five-year term.

At his final rally in the capital Bamako on Friday, Keita struck a confident tone.

"Some people were sceptical that these elections could take place. Some called on me to withdraw," he said above the din of his supporters' vuvuzelas. "Let them understand that we had the capacity to organise credible elections and we have done so."

Despite the militant threat, Malian polls have generally gone peacefully without the post-election violence common to many countries in the region.