At least six UN peacekeepers were killed by militants in Mali's restive northern region, the UN mission in Mali, MINUSMA, said.Five others were also wounded when a UN convoy was ambushed in the morning near the city of Timbuktu, MINUSMA said on Thursday, Xinhua reported.The UN mission said the wounded were being evacuated while reinforcements including helicopters had been sent to the area.Two UN vehicles were destroyed in the attack, said the mission.MINUSMA head Mongi Hamdi has condemned the incident as a "terrorist attack.""I strongly condemn this new terrorist attack on our peacekeepers. Those responsible for this heinous crime must be identified and brought to justice as soon as possible, he said.The attack was one of the deadliest for the UN peacekeepers in Mali. About 40 peacekeepers have been killed since MINUSMA was established in 2013, according to UN figures.