Niger's coup leaders that toppled President Mohamed Bazoum said late Sunday they would "prosecute" him for "high treason" and "undermining the security" of the country in a statement read on national television. 

"The Nigerien government has so far gathered ... evidence to prosecute the deposed president and his local and foreign accomplices before the competent national and international bodies for high treason and undermining the internal and external security of Niger," said Colonel-Major Amadou Abdramane. 

The military in Niger detained Bazoum on July 26 and chose Abdourahamane Tchiani, former leader of the country's presidential guard, to lead the National Council for the Safeguard of the Homeland (CNSP), a governing body the soldiers established after the coup, which has been exercising legislative and executive authority.

The CNSP said the soldiers overthrew Bazoum because of "the continued deterioration of the security situation" and "poor economic and social governance" in the country.

Bazoum, his wife and his son have since been held in custody at his official residence in Niger's capital, Niamey. 

According to media reports, the detained president received a medical visit on Saturday. His doctor told Radio France Internationale (RFI) that "the president's morale is high."

World leaders and international organizations have repeatedly voiced concern regarding his condition and condemned the coup. 

Last week, the Economic Community of West African States (ECOWAS) said it has resolved to activate its standby force in response to the coup in Niger while underscoring its continued commitment to restoring constitutional order in the country through peaceful means.

The bloc announced sanctions on Niger's military leaders involved in the recent coup in July. 

(With input from agencies)