Niger has defaulted on debt instruments worth about half a billion dollars since the country's July coup, according to West Africa's currency union.

Umoa-titres, which manages West African Economic Monetary Union (WAEMU)operations, has published eight notices to investors since the beginning of the year stating that Niger has been "unable to meet its financial obligations on the Government securities market".

Since the July coup that brought a military regime to power, the total unpaid sums amount to more than 313 billion CFA francs ($515 million).

"It should be noted that this payment incident comes at a time when the State of Niger is subject to sanctions imposed on it by the Conference of Heads of State and Government of the West African Economic and Monetary Union," Umoa-titres said Monday.

Umoa-titres is responsible for managing and promoting public securities in the WAEMU zone, which includes eight West African countries that use the CFA franc as their currency -- Ivory Coast, Senegal, Togo, Burkina Faso, Mali, Guinea-Bissau, Niger and Benin.

Last week, Moody's downgraded Niger's credit risk rating from Caa2 to Caa3 for the third time since the coup.

"The sanctions imposed since the end of July 2023 in response to the military coup have exacerbated economic difficulties and further hampered the government's potential ability to meet its obligations," the rating agency said following its decision.

The Economic Community of West African States (ECOWAS) suspended Niger's membership and imposed severe economic sanctions following the coup.

Niger is ruled by military leaders who overthrew the elected president Mohamed Bazoum on July 26, and have held him in detension ever since.

Niger and its two neighbours, Mali and Burkina Faso, who are also run by military coup leaders, announced at the end of January that they would withdraw from ECOWAS "without delay".