The Economic Community of West African States (ECOWAS) has scheduled the summit to discuss its standoff with the Niger junta, which seized power on July 26 and ignored an August 6 deadline to stand down. The coup leaders have vowed to resist external pressure to reinstate ousted President Mohamed Bazoum, after ECOWAS imposed sanctions and Western allies suspended aid.

"There's no doubt that diplomacy is the best way to resolve this situation," US Secretary of State Antony Blinken said on Tuesday.

US acting deputy secretary of state Victoria Nuland flew to Niamey on Monday. She held "frank and difficult" talks with senior junta officials but said they did not take up US suggestions for restoring democratic order.