Niger's new junta has accused former colonial ruler France of wanting to "intervene militarily" to reinstate deposed President Mohamed Bazoum.
"In its search for ways and means to intervene militarily in Niger, France with the complicity of some Nigeriens, held a meeting with the chief of staff of the Nigerien national guard to obtain the necessary political and military authorisation needed," said a statement read out on national television.
In another statement, the putschists accused the security services of an unnamed Western embassy of firing teargas on pro-coup demonstrators in the capital Niamey.
It said six people had been hospitalised after the incident.
French President Emmanuel Macron had vowed "immediate" action if French citizens or interests were attacked in Niger, after thousands of Nigeriens rallied outside the French embassy.
Anti-French sentiment runs high in some former African colonies as the continent becomes a renewed diplomatic battleground, with Russian and Chinese influence growing.
France has some 1,500 troops in the West African nation, which is one of its last allies in the Sahel region, after French forces had to withdraw from neighbouring Mali earlier this year.
Following Mali and Burkina Faso, Niger has become the third country in the Sahel to be undermined by jihadist attacks linked to the Islamic State group and al-Qaeda.
The EU said it would hold Niger's putschists responsible for all attacks on civilians, diplomatic personnel and embassies after pro-coup demonstrators rallied outside the French embassy.
The European Union will also "quickly and resolutely" apply the decision of the West African regional bloc ECOWAS to apply economic sanctions on Niger, EU foreign policy chief Josep Borrell said in a statement.
Read more: West Africa threatens force on Niger coup leaders
West African nations imposed sanctions and threatened force if Niger's coup leaders fail to reinstate President Bazoum within a week.
The 15-nation ECOWAS bloc's response to the Sahel region's seventh coup of recent years came as crowds in Niamey burned French flags and stoned the former colonial power's mission, drawing tear gas from police.
Images showed fires at the embassy walls and people being loaded into ambulances.
ECOWAS and the eight-member West African Economic and Monetary Union said that with immediate effect borders with Niger would be closed, commercial flights banned, financial transactions halted, national assets frozen and aid ended.
Military officials involved in the coup would be banned from travelling and have their assets frozen, it added.
