The United Nations peacekeeping mission in Mali says four people have been killed in two attacks on U.N. projects in Mali.

The spokesman for the mission said a rocket or mortar attack on Tuesday night killed one U.N. peacekeeper and gravely wounded three others at the mission's camp in the city of Gao. It said more than 10 peacekeepers were lightly wounded.

The spokesman's statement said a separate attack shortly afterward on a local service provider for the U.N.'s mine-defusing agency killed two Malian security guards and an international expert with the company.

The U.N. gave no information about the attackers.

Islamic extremists have been attacking international peacekeepers and Malian soldiers working to stabilize the north three years after a French-led military campaign ousted the jihadists from power.