This is contained in a document from the World Humanitarian Summit, ongoing in Istanbul, Turkey, made available to reporters in New York.
The document said Mr. Issoufou made this known on Tuesday during a high-level leaders’ round table titled “Uphold the Norms that Safeguard Humanity”.
He said the Nigerien government would ensure the militants are tried by the ICC.
“This is something that all countries should do,” he said.
The best way to protect civilians, he added, was to ratify humanitarian conventions.
“Political, military and administrative authorities must be aware of pledges made by Governments and of the sanctions provided for under those conventions,” he said.
Mr. Issoufou added that all countries must take on commitments to respect international humanitarian law and human rights instruments, as well as guarantee that populations in need received humanitarian aid.