There is "no doubt" that Nigeria-based Boko Haram Islamists were behind the suicide bombings that killed 23 people and injured over 100 others in the Chadian capital Monday, French President Francois Hollande said.

"There is no doubt that Boko Haram is responsible and will be brought to justice for this new humanitarian horror," Hollande said at a press conference in Algiers after meeting his Algerian counterpart Abdelaziz Bouteflika during a visit that focused on the threat posed by jihadists in the region.