(AFP) - Niger's military rulers were on Monday in defiance of an ultimatum to restore the elected government as the threat of possible military intervention was still on the table.

No foreign forces were visible on the streets of the capital Niamey after the deadline came and went on Sunday, but the ECOWAS regional bloc has not yet responded publicly to the coup leaders' recalcitrance.

A source close to the Economic Community of West African States (ECOWAS) said an immediate military intervention to restore President Mohamed Bazoum is not being envisaged at this stage.

But a summit of its member nations' leaders is possible in coming days to decide on next steps, the source added, as nations like Italy and Germany spoke in favour of a diplomatic solution in the trouble west African nation.

Neighbouring Mali said it and Burkina Faso -- who have both been suspended from West African bloc ECOWAS over their own military coups -- were sending a joint official delegation to Niamey to show "solidarity (with) the people of Niger".

They have said military intervention would be tantamount to a declaration of war.

Niger's military leaders have closed the nation's airspace and on Monday its skies were clear of traffic, according to the flight tracking website Flightradar24.

Italy urged ECOWAS to extend the deadline and seek a diplomatic solution, with a similar call from Germany.

"We support ECOWAS in its mediation efforts, which are still ongoing," a foreign ministry spokesman told a press briefing.

- Constitutional order -

Algeria, which shares a long land border with Niger, has also cautioned against a military solution, which he said would be "a direct threat to Algeria".

Senators in regional heavyweight Nigeria, whose president is currently ECOWAS chairman, called for everyone to focus on the "political and diplomatic option".

Just before the ultimatum expired on Sunday, Niger's military rulers closed the Sahel country's airspace and warned any attempt to enter it would meet with an "energetic and immediate response".

They said there had been a "pre-deployment in preparation for intervention" made by two Central African countries, without naming them, and warned: "Any state involved will be considered co-belligerent."

Former colonial power France, with which Niger's new rulers have broken military ties, said it would "firmly" back whatever course of action ECOWAS took after the deadline expired.

Ivory Coast President Alassane Ouattara called on Sunday on the coup leaders to stand down.

"We condemn the attempted coup in Niger, which poses a serious threat to peace and security in the sub-region," Ouattara said, adding it was "essential" to "constitutional order" that Bazoum be allowed to govern.

The Niger coup was the latest of several to hit Africa's Sahel region since 2020.

Niger has played a key part in Western strategies to combat jihadist insurgencies that have plagued the Sahel since 2012, with France and the United States stationing around 1,500 and 1,000 troops in the country, respectively.

France has already evacuated hundreds of its citizens from Niger since the coup, and on Sunday, Italy's defence ministry said it had flown 65 military personnel from Niger, along with 10 US military personnel.

© Agence France