By Reuters BAMAKO (Reuters) - Gunmen on motorbikes have killed more than 30 Tuareg civilians this week in northern Mali, where clashes over land and scarce water are common, an official said on Wednesday. The violence compounds an already dire security situation in the desert region used by jihadist groups to launch attacks in Mali and across West Africa. The identity of the assailants was unknown, but disputes between the nomadic Tuareg and herder Fulani ethnic groups have killed several hundred and displaced thousands over the past year. Menaka town mayor Nanout Kotia told Reuters 34 Tuareg were killed in two nearby villages on Tuesday. “Armed men riding several motorbikes, as is their custom, encircled these villages and shot at the people. The death toll is high,” Kotia said by telephone. The attack follows the killing of more than 40 Tuareg civilians in the same area in mid-December and the death of 15 Fulani civilians in Mali’s central Mopti region in the same month. Mali has been in turmoil since Tuareg rebels and loosely allied Islamists took over its north in 2012, prompting French forces to intervene to push them back the following year. They have since regained a foothold in the north and center, tapping into ethnic rivalries to recruit new members.