Bamako (AFP) - Al-Qaeda and the Islamic state group have turned their guns on each other in the Sahel, according to experts, fracturing a period of cooperation that has held for years.
The rival jihadist outfits have squared off in other theatres before, such as in Syria. But they have often worked in tandem in the Sahel, coordinating attacks, and even swapping fighters.
The semi-desert African region has seen years of conflict with Islamic militants, who first emerged in northern Mali in 2012 before sweeping into the centre of the country, and neighbouring Burkina Faso and Niger.
Thousands of soldiers and civilians have been killed to date and hundreds of thousands have fled their homes.
But since the beginning of the year, sporadic clashes between al-Qaeda and Islamic State affiliates appear to have escalated into full-blown combat in central Mali and Burkina Faso.
Few details have emerged from this internecine jihadist struggle, with much of it taking place in volatile areas already beset by bandits and ethnic militias, and regular clashes with national armies.
Experts and local officials point to disputes over territorial expansion or access to fodder crops as some of the reasons behind the fighting.
Mahamat Saleh Annadif, the United Nations special representative in Mali, said that the jihadist civil war is "no longer a secret".
"We don't know where it's going to end, each one wants to get the upper hand over the other," he said, explaining that the groups are fighting over land.
Al-Qaeda-affiliated jihadists -- now grouped under an alliance named GSIM -- first emerged in northern Mali in 2012 and then established themselves in central Mali in 2015.
The Islamic State group's history in the region is shorter. Islamic militant Abou Walid Al-Sahraoui founded the region's franchise in 2015, and it is now active in the border regions linking Mali, Burkina Faso and Niger.
- Fair-weather friends -
Neither al-Qaeda nor the Islamic State group ever formally inked an alliance in the Sahel, according to a western diplomat in Mali's capital Bamako.
But that did not stop them from working closely together, he said, pointing to joint raids and fighters who would pass from one group to another.
The diplomat added that a person's reason for joining one or the other group is often tied to local circumstance, such as belonging to a marginalised ethnic group or not having a job.
Likewise, reasons for conflict are also often local, said Ibrahim Maiga, a researcher at the Institute for Security Studies in Bamako.
"These conflicts should not only be understood through an ideological prism," he said.
For example, during the dry season at the beginning of the year, fighting often erupts in central Mali over a fodder crop grown in the Niger river delta, called bourgou.
A security expert in the central Malian city of Mopti, who requested anonymity, told AFP that jihadists are fighting over the bourgou-growing areas "like everyone else".
- Propaganda war -
Clashes between the two jihadist groups began after Islamic State fighters crossed into the Dialloube region of central Mali from Burkina Faso at the start of the year, according to a local official who declined to named.
The militants went "from village to village propagating their message," the official added.
Dialloube is traditionally the territory of Katiba Macina, a jihadist outfit which is part of al-Qaeda-affiliated GSIM alliance.
A security advisor who works in Mopti, and who declined to be named, told AFP that "over 60 jihadists were killed" in fighting in the area in mid-March.
In neighbouring Burkina Faso, Islamic State claimed that in late April its fighters had killed "over 35" GSIM militants near the Malian border.
It said it had also sent a suicide car bomber against a GSIM base in the same area.
Despite the grisly picture painted by the propaganda, Maiga, the Bamako researcher, said information coming from war-torn parts of the Sahel is often exaggerated.
The United Nations, in a recent internal report, also pointed towards a "lack of intelligence" concerning several areas of central Mali.
Uncharacteristically for the usually media-savvy jihadists, neither al-Qaeda nor the Islamic State group has yet published footage of their clashes either.