Three candidates have launched legal challenges disputing the result of last week's presidential election, AFP news agency reports.

A second round run-off is due on Sunday after incumbent President Ibrahim Boubacar Keita took 41.4% of the vote. He's set to face Soumaila Cissť, who polled 17.8%.

But Mr Cisse, along with third-placed Aliou Boubacar Diallo and fourth-placed Cheick Modibo Diarra, has filed a case in court.

AFP quotes his spokesman as saying that Mr Cissť is alleging that ballot boxes were stuffed, along with other irregularities.

Voting in the election on 29 July did not take place at about 700 polling stations following threats by armed groups.