Niger's military leader vowed late Sunday to prosecute Western-backed ousted President Mohamed Bazoum for "high treason" and slammed West African leaders for imposing sanctions against the country.

The Economic Community of West African States (ECOWAS) imposed sanctions against Niger in response to the coup and has not ruled out using military force against the army officers who toppled Bazoum on July 26.

The West African bloc has approved the deployment of a "standby force to restore constitutional order" in Niger as soon as possible but claimed that it remains committed to finding a diplomatic solution to the crisis.

Niger's military leaders said they would prosecute Bazoum "for high treason and undermining the internal and external security of Niger," according to a statement read out by Colonel-Major Amadou Abdramane on national television.

Bazoum, 63, and his family have been held at the President's official Niamey residence since the coup. A member of his entourage said he saw his doctor on Saturday.

"After this visit, the doctor raised no problems regarding the state of health of the deposed president and members of his family," the military said.

They also said sanctions imposed against Niger had made it difficult for people to access medicines, food, and electricity and were "illegal, inhumane and humiliating."

The comments came just hours after religious mediators met with coup leader General Abdourahamane Tchiani, who affirmed that military leaders were open to a diplomatic breakthrough.

Tchiani "said their doors were open to explore diplomacy and peace in resolving the matter," indicated Sheikh Bala Lau, a day after his Nigerian Muslim delegation held talks in the capital Niamey.

Tchiani "claimed the coup was well intended" and that the plotters "struck to stave off an imminent threat that would have affected" Nigeria, as well as Niger, according to Lau's statement.

But Tchiani said it was "painful" that ECOWAS had issued an ultimatum to restore Bazoum without hearing "their side of the matter," the statement added.

The Muslim leaders visited Niamey with the blessing of Nigerian President Bola Tinubu, who adopted a firm stance against the coup and is also head of ECOWAS.

The bloc has severed financial transactions and electricity supplies and closed borders with landlocked Niger, blocking much-needed imports to one of the world's poorest countries.

On July 30, ECOWAS issued a seven-day ultimatum to restore Bazoum or face a potential military attack, but the deadline expired without the new rulers backing down.

The bloc canceled a Saturday crisis meeting on the coup due to be held in Ghana's capital Accra for "technical reasons".

It is noteworthy that demonstrations in favor of the new military rulers have become a common sight in Niamey. On Sunday, thousands of people attended concerts at the Seyni Kountche Stadium in support of the National Council for the Safeguard of the Homeland (CNSP), the generals who have taken power.

The prospect of a military invasion against Niger to reinstate Bazoum has divided ECOWAS members and drawn warnings from foreign powers including Russia and Algeria.

Niger's neighbors Mali and Burkina Faso, also ruled by military governments who seized power in coups, have warned that an intervention would be tantamount to a declaration of war on them.

Read more: Nigeriens protest against ECOWAS plans of armed intervention