The ex-rebels from the Coordination of Azawad Movements (CMA) in northern Mali said Monday they were in a "time of war" with the ruling junta, in a statement received by AFP.
The region has seen a resurgence of tension in recent weeks, triggered in part by the impending pullout of UN peacekeeping troops from Mali.
The CMA, an alliance of Tuareg-dominated groups seeking autonomy or independence from the Malian state, called on all residents of the northern Azawad region to "go to the field to contribute to the war effort" in a statement also distributed on social media.
In the statement, the CMA said its purpose was "defending and protecting the homeland and thus regaining control of the entire territory".
It was the first document signed by a group calling itself the "Azawadian National Army".
In its statement, the CMA also called for civilians to stay away from "Wagner terrorists".
The military junta in Mali are widely believed to have secured support from the Russian Wagner paramilitaries.
Mali underwent a military takeover in August 2020, followed by a second in May 2021.
A 2015 peace deal -- the so-called Algiers agreement between the government and the CMA -- has been hanging by a thread amid renewed violence.
The CMA said Saturday it had shot down an army plane in the Gao region after they came under attack.
And the governorate of the eastern Gao region on Sunday said it had installed a 30-day overnight curfew between 8:00 pm and 6:00 am with only security vehicles exempted.
In late August, Mali's junta had called on the armed groups in the north to renew dialogue and the ailing peace deal, amid fears of fresh hostilities after the UN peacekeeping force withdraws.
The UN peacekeeping mission, known as Minusma, has until December 31 to exit Mali after a decade of struggling to stabilise the country's security environment amid separatist and jihadist rebellions.
The 13,000-person mission was ordered to withdraw earlier this year under the demand of Mali's ruling junta, following the pullout of French troops in 2022.