Dozens of people -- some of them unarmed -- were killed in a remote part of northern Mali as Islamist fighters backed by Al-Qaeda's north African branch routed Tuareg rebels, a security source said Tuesday.
The Malian security source called the killings "a real massacre" and said the bodies of some of those slain in violence that began Friday still dotted the arid village of Menaka, in northeastern Mali's Gao region, just above the Niger border.
"Unarmed people were shot in cold blood," the source said. "There needs to be a genuine international investigation to find out what happened at Menaka."
Other witnesses and fighters confirmed that dozens had been killed.
The latest violence in northern Mali, in the hands of Islamist rebels since shortly after a March coup in Bamako, comes amid growing international momentum to reclaim the sparsely populated desert land.
A hodgepodge of Islamist and Tuareg groups, some homegrown, others foreign, have seen alliances rise and falter in the months of chaos.
Starting Friday, local Tuareg rebels who want to establish an independent homeland called Azawad battled with the Islamist group the Movement for Oneness and Jihad in West Africa (MUJAO), which is backed by Al-Qaeda's north African wing, Al-Qaeda in the Islamic Maghreb (AQIM).
The fighting was focused in Ansongo, about 200 kilometres (120 miles) west of Menaka, and in Menaka itself, where the Tuareg rebels had hoped to establish a base from which to launch counter-offensives against the Islamists.
A lawmaker for the Menaka district, Bajan Ag Hamato, said some of his fellow Tuareg had been killed "defending the town against MUJAO", including local political leader Alwabegat Ag Salakatou and six of his entourage.
He said that although they had been labelled as members of the Tuareg rebels' Azawad National Liberation Movement (MNLA), "in reality they were local patriots who wanted to defend their town".
It was not immediately possible to confirm who had been killed in the violence. A security source from Niger said four seriously injured MNLA fighters had been evacuated to Niger's capital Niamey.
The MNLA had previously claimed its fighters killed 65 MUJAO and AQIM members, suffering just one death and 13 injuries on its side, but MUJAO said it killed more than 100 MNLA fighters and took 20 prisoners.
The fighting picked up again Monday as the Islamist groups were bolstered by reinforcements, witnesses told AFP, saying the MNLA were chased from the town.
A regional security source on Tuesday said the Islamists controlled most of Menaka.