Authorities say two United Nations peacekeepers from Chad have been killed when their foot patrol was ambushed in the Kidal region of northern Mali.

The U.N. mission known as MINUSMA said in a statement they were killed early Tuesday outside Aguelhok. A third peacekeeper was wounded.

There is no immediate claim of responsibility, though jihadists are active in the area and religious extremism is also mounting. Last week, an unmarried couple accused of having an affair was stoned to death in the region, according to witnesses.

Islamic extremists seized control of Mali's north in 2012 but were forced out of strongholds a year later by a French-led military intervention. But jihadists continue to attack Malian soldiers and U.N. peacekeepers.

The U.N. mission in Mali is the world's deadliest active mission.