The operation was launched on May 5 in the Nord and Sahel regions, bringing together conventional and special forces, the air force and gendarmerie, a police unit that is under military command, it said in a statement.

Named Houne -- Dignity in the Fula, or Peul, language -- the operation is expected to last more than a month, a senior security source told AFP

"More than 20 terrorists have been neutralised" and four of their bases or positions have been destroyed, the source said, adding that communications equipment, weapons, ammunition and means of transport had also been seized.

The armed forces have made many announcements of similar operations in the past, but are failing to stem a mounting toll inflicted by the Sahel country's five-year-old jihadist crisis.

Around 1,300 people have died and more than a million have fled their homes.

On Saturday, three civilians were killed in Tin-Akoff, in the Nord region, while three soldiers were hurt by a highway bomb in Mansila in the province of Yagha in the east.