While Washington believes the crisis can be resolved, it has suspended millions of dollars in aid until President Mohamed Bazoum is reinstated.

West African countries will meet on Thursday to discuss the coup having warned the junta of military action.

The coup leaders responded to the threat from the Ecowas bloc of African states by closing Niger’s airspace.

Speaking at a US State Department news conference on Monday, spokesman Matthew Miller said “the window of opportunity is definitely still open”.

He added that the US believes “the junta should step aside and let President Mohamed Bazoum resume his duties” and the US remained in contact with the deposed leader.

America’s top diplomat, Secretary of State Anthony Blinken, told BBC News Ecowas had Washington’s full backing for its approach to the crisis in Niger.

“It’s very important that that constitutional order be restored and right now I think Ecowas is playing a very important role in moving the country back in that direction,” Mr Blinken said.

The European Union also said there remained a chance to restore Niger’s democratically elected government.

“The EU still thinks there is some room for mediation until Thursday 10 August,” a EU spokesperson said, referring to Thursday’s Ecowas summit.

The growing instability in the region compelled former colonial power France on Monday to warn its citizens against travelling to the Sahel region, and for those still there to be cautious due to anti-France sentiment.

“It is essential to limit travel, to stay away from any gatherings and to keep themselves regularly informed of the situation,” read a statement from the foreign ministry.

The junta in Niger on Sunday said it had information that “a foreign power” was preparing to attack the country, following reports that military chiefs from Ecowas, a bloc of 15 countries including Nigeria, Senegal, Togo and Ghana, had drawn up a detailed plan for use of force.

Ecowas had issued a 23:00 GMT Sunday deadline to Niger’s junta leaders to stand down and restore the elected president.

Earlier, Abdel-Fatau Musah, the bloc’s commissioner for political affairs, peace and security, said that while “all the elements” had been worked out about an “eventual intervention”, the body wanted “diplomacy to work”.

Over the weekend Nigeria’s Senate discussed the situation in Niger after President Bola Tinubu wrote to it about the Ecowas resolutions imposing sanctions and the possible use of military force.

Local media report there was strong opposition to military intervention, especially from senators representing states near the long border the two countries share.

President Tinubu has been especially vocal in demanding that the Niger military leave power and has threatened to use force if they do not – but he needs approval from the National Assembly for any foreign military intervention.

Source: BBC