Late on Sunday, the coup leaders who overthrew Bazoum announced that they had amassed sufficient evidence to bring charges against him for "high treason and undermining the internal and external security of Niger.”

This was based on "contacts" Bazoum made with "nationals... foreign heads of state... (and) officials in international organisations," according to the document.

ECOWAS said it learned of the threats "with stupefaction" in a statement on Monday.

“It represents yet another form of provocation and contradicts the reported willingness of the military authorities in the Republic of Niger to restore constitutional order through peaceful means,” the bloc said.

Since the coup, Bazoum and his family have been detained at the president's official mansion, raising concerns about his living conditions.