The Permanent Strategic Framework (CSP), an alliance of rebel forces, said it had decided to set up roadblocks across all roads leading to northern borders with Mauritania, Algeria and Niger.
It would cover roads leading out of the cities of Menaka, Kidal, Gao, Timbuktu and Taoudeni, a statement from the CSP said.
This blockade would cover all products and all means of transport, the statement added.
The mainly Tuareg rebel forces have in recent weeks lost ground to a Malian army offensive that in mid-November led to their recapture of the northeast city of Kidal.
Fighting between the separatists and government troops broke again in August after eight years of calm, as both sides scrambled to fill the vacuum left by the withdrawal of UN peacekeepers known as the United Nations Multidimensional Integrated Stabilization Mission in Mali, or MINUSMA.
The MINUSMA force packed up and left at the behest of Mali's military rulers in Bamako, where the colonels seized power in 2020.
It was the army's air power, including planes and drones, that helped make its recent gains against the rebel forces.
Mali's army was also backed by mercenaries from Russia's Wagner force, according to the rebels and local elected officials, but the regime denies the presence of the controversial paramilitary group.
There have been accusations of atrocities committed against civilians during the recent offensive by Mali's army and the Russian force, which the authorities have repeatedly denied.
Getting reliable information from the vast, northern part of Mali is extremely difficult because of its inaccessibility, lack of security and the muzzling of dissident voices there.
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