France handed back the military base in northeastern Mali on Monday, as part of its withdrawal from Mali after almost a decade leading the Barkhane anti-insurgency force against jihadists.

The French army said before leaving that it would be "very vigilant to information attacks", that could include the organisation of anti-France demonstrations or the burying of bodies to make it look like France carried out atrocities.

"Several dozen" Russian mercenaries of the private military company Wagner Group arrived on Wednesday, sources briefed on the situation who asked not to be named told AFP, while a local source said they had seen "a dozen" Russians.

Western nations have repeatedly accused Moscow of sending mercenaries from the Wagner Group, notorious from its past operations in Africa, Syria and Ukraine, into Mali to help prop up the military junta.

The departure from the Menaka base "was conducted in good order, safely and in transparent fashion in a context where the Barkhane force is faced with regular information attacks to try and tarnish its actions and credibility," said French army spokesman Pascal Ianni earlier in the week.

In April, the French army said it had filmed Russian mercenaries burying bodies near the Gossi base in northern Mali to falsely accuse France's departing forces of leaving behind mass graves.

The video came after a Twitter user posted images of pixelated corpses buried in sand and accused France of atrocities.

France's general staff called the Twitter video an "information attack" and said the profile was "very probably a fake account created by Wagner".

Relations between Bamako and Paris have gone steadily downhill, propelled by the junta's resistance to setting an early date to restore civilian rule and Bamako's charges that France was inciting the region to take a hard line against it.

The bust-up accelerated last year, as the junta wove closer ties with Moscow, bringing in "military instructors" that France and its allies condemned as mercenaries hired from the pro-Kremlin Wagner group.

In January this year, the French ambassador to Bamako was expelled and the following month France announced the pullout of its troops from Mali.