Constitutional reform is the first major step in the military's plans to justify continuing to govern until 2024, following the overthrow of former president Ibrahim Boubacar Keita in August 2020.

"The Call of February 20" movement said in a statement sent to AFP on Monday that the army had no mandate "to plunge us into the unknown, or even to submit us to a state of no-rule of law".

The statement said the referendum was "illegal" and superfluous and demanded a vote for an early return of a civilian government in the insurgency-wracked west African nation.

The Call of February 20 is a bid by several groups and figures who have kept their distance from the military authorities to bring together political parties and civil society organisations.

Already on Saturday some 20 religious, cultural and political associations announced they were joining forces to have the principle of a secular state removed from the draft constitution.

The movement said the draft "seriously" threatens the independence of the judiciary and "organises impunity for certain personalities".

According to the draft, any coup is an "inalienable crime", but it extends an amnesty to the colonels who seized power nearly three years ago.

The draft would also significantly strengthen the power of the president.

The movement said "no condition is right" to stage a referendum in a nation which does not control "more than two-thirds" of its territory, a claim the junta rejects.

"Without any doubt, we will prevent by legal means the holding of this irregular referendum," the movement vowed.

Mali "does not face a problem with the constitution, the only alternative is to turn the page on this transition which is as disconnected to the principles of the rule of law as it is to republican values."

The junta intends to hold elections in February 2024 to restore a civilian government in Bamako.