Niger on Sunday shut down its airspace due to the threat by the West Africa regional bloc military intervention after coup leaders rejected a deadline to reinstate the country's removed president.

Hundreds of junta supporters came to a stadium in the nation's capital, Niamey, to applaud the group's resolve to defy pressure to resign by Sunday following the coup on July 26.

The Sahel area, one of the poorest in the world, has been shaken by the coup, the seventh in West and Central Africa in the last three years.

Niger is significant to the U.S., Europe, China, and Russia because of its oil and uranium resources and its leadership in the fight against Islamist militants.

A potential military action plan, including when and where to strike, has been agreed upon by the defence chiefs of the Economic Community of West African States (ECOWAS) if the detained president, Mohamed Bazoum, is not freed and reinstalled by the deadline.

"In the face of the threat of intervention that is becoming more apparent ... Nigerien airspace is closed effective from today," a junta representative said in a statement on national television on Sunday evening.

Further, he said there had been a pre-deployment of forces in two Central African countries in preparation for intervention but did not give details.

"Niger's armed forces and all our defence and security forces, backed by the unfailing support of our people, are ready to defend the integrity of our territory," he said.

A request for comment regarding ECOWAS's upcoming actions and the time on Sunday its deadline expires still needs to be answered.

A spokesperson stated that a statement will be released at the end of the day.

Over 100 junta supporters set up a picket this weekend near an air base in Niamey, blaring military music and blowing vuvuzela horns as part of a citizen movement to provide nonviolent resistance in favour of the junta if necessary.

Many of the protesters' angry cries of "Vive Niger" appeared to be directed against ECOWAS and the former colonial power France, which announced on Saturday that it would help regional efforts to overthrow the coup without saying if that support would entail military intervention.

"The Nigerien people have understood that these imperialists want to bring about our demise. And God willing, they will be the ones to suffer for it," said pensioner Amadou Adamou.