Mali and Burkina Faso will send a joint official delegation to Niger to express their solidarity.
The declaration comes a day after the generals who took control of Niger disobeyed a warning to restore the elected leader or risk armed intervention from other West African states.
The military junta declared that it had shut down airspace over Niger and was getting ready to defend its territory.
Members of the regional alliance Ecowas are divided on whether to take military action despite the ultimatum.
Those calling for the reinstatement of President Mohamed Bazoum include Nigeria and Ivory Coast.
However, the military governments in Mali and Burkina Faso have declared they would support the coup leaders if they were attacked.
Source-BBC
