Russia has warned that military intervention in Niger would lead to a “protracted confrontation” after regional bloc Ecowas said it would assemble a standby force.
Such an intervention would destabilise the Sahel region as a whole, the Russian foreign ministry said.
Russia does not formally back the coup.
But the US, which backs efforts to restore deposed leader Mohamed Bazoum, says its Wagner mercenary group is taking advantage of the instability.
On Friday coup supporters, some waving Russian flags, protested at a French military base near the capital NIamey, some chanting “down with France, down with Ecowas”.
Both France and the US operate military bases in Niger and they have been used to launch operations against jihadist groups in the wider region.
Military officials from Ecowas countries are reportedly set to meet on Saturday to draft plans for a military intervention.
The bloc has said it remains open to finding a diplomatic solution to the crisis, but Nigeria’s President Bola Tinubu said on Thursday that “No option is taken off the table, including the use of force as a last resort”.
The US has not explicitly backed military action but has called on the junta to step aside and allow the restoration of the country’s democratic constitution.
The Niger junta has not responded to the latest statements from Ecowas leaders.