The so-called "G5 Sahel" countries just south of the Sahara -- Burkina Faso, Chad, Mali, Mauritania and Niger -- have pledged to fight jihadists on their own soil with instability and Islamist attacks on the rise.
Macron is joining the heads of state of these nations in Bamako for a special summit where France's full support for the force will be announced, with a focus expected on providing equipment.
With its base in Sevare, central Mali, the 5,000-strong G5 Sahel force aims to bolster the 12,000 UN peacekeepers and France's own 4,000-strong military operation known as Barkhane operating in the region.
Serge Michailof, a researcher at the Paris-based IRIS institute, described the EU contribution as "a joke" in the context of the EU's "very deep pockets".
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"This force is going to cost USD 300-400 million at the very least," he told AFP, and would be especially difficult for certain nations involved which are already "choking" on military spending.
Deby and Macron are due to meet on the margins of the Bamako summit to discuss the issue, according the French presidency, as Chad's military is widely viewed as the strongest of the five Sahel nations.
Macron visited Gao in northern Mali in May, his first foreign visit as president outside Europe, and said French troops would remain "until the day there is no more Islamic terrorism in the region".
That mission evolved into the current Barkhane deployment launched in 2014 with an expanded mandate for counter-terror operations across the Sahel.
The new Sahel force will support national armies trying to catch jihadists across porous frontiers, and will work closely with Barkhane.
Operations across Burkina Faso, Niger and Mali, all hit with frequent jihadist attacks, will be co-ordinated with French troops, a source in the French presidency told AFP earlier this week, while help would be given to set up command centres.