French Defence Minister Jean-Yves Le Drian visited Mali on Monday to show his support for a landmark peace deal agreed in the former colony to end years of unrest and ethnic divisions.

Just two days after Mali's Tuareg-led rebel alliance added its signature to the Algiers Accord -- aimed at stabilising Mali's restive northern desert -- Le Drian travelled to the northern African country to offer France's help in implementing the fragile agreement.

Addressing French troops stationed in the northern town of Gao, he warned of challenges ahead and said now was not the time "to drop our guard".

"The efforts we are carrying out alongside our partners must continue," he said, before holding talks with Malian President Ibrahim Boubacar Keita in the capital.

France currently has 1,350 soldiers deployed in Mali as part of the French-led counter-terrorism Operation Barkhane, which covers a broader zone that includes the Sahel and Saharan regions of northern Africa.

With the Malian army still largely absent in the north, France has pledged to boost its military support for the UN's MINUSMA mission, which has been the repeated target of deadly attacks in recent months.

"The failure of MINUSMA will also be our failure. But its success is tied to our success," Le Drian said in Gao.

Underscoring the threat, a private Mauritanian news agency said Monday it had obtained a video showing a South African and a Swede who were kidnapped in Mali in 2011 and are being held by Al-Qaeda.

The video appeared to show Stephen Malcolm McGown, from South Africa, and Swedish citizen Johan Gustafson in good health, an employee at the Sahara Medias website told AFP.

The peace accord, hammered out over months under the auspices of the UN, calls for the creation of elected regional assemblies but stops short of autonomy or federalism for northern Mali, known by locals as Azawad.

The agreement had already been signed in May by the government and loyalist militias but the Coordination of Azawad Movements (CMA), a coalition of rebel groups, had been holding out until amendments were agreed.

The rebels finally agreed to commit on June 5 after winning a stipulation that its fighters be included in a security force for the north, and for residents of the region to be represented better in government institutions, among other concessions.

Mali was shaken by a coup in 2012 that cleared the way for Tuareg separatists to seize towns and cities of the north, an expanse of desert the size of Texas.

Al-Qaeda-linked militants then overpowered the Tuareg, taking control of the region for nearly 10 months until they were ousted in a French-led military offensive.