Nigeria has denied accusations from Niger's military leader, Brig Gen Abdourahmane Tchiani, of colluding with France to destabilise the junta-led nation.

In a Christmas Day interview, Gen Tchiani accused France of allying with militant groups in the Lake Chad region to undermine Niger's security, allegedly with Nigeria's knowledge.

"Nigerian authorities are not unaware of this underhanded move," Gen Tchiani was quoted as saying by AFP.

In response, Nigeria's National Security Adviser, Nuhu Ribadu, told BBC Hausa that the allegations were "baseless" and "false".

Mr Ribadu said Nigeria would never "sabotage Niger or allow any disaster to befall it".

Nigeria's Information Minister, Mohammed Idris, said the allegations were unfounded and a "diversionary tactic aimed at covering his administration's failures".

"These claims exist solely in the realm of imagination. Nigeria has never engaged in any alliance, overt or covert, with France — or any other country — to destabilise Niger Republic," Idris said.

Idris also denied sabotaging Niger's pipeline and agriculture, which it was accused of.

Gen Tchiani's allegations have worsened diplomatic tensions with Nigeria, already strained since the 2023 military coup that ousted ex-president Mohamed Bazoum.

West Africa's regional bloc, Ecowas, led by Nigeria's President Bola Tinubu, imposed economic sanctions on Niger and threatened military intervention if constitutional order was not restored.

Ecowas came to Nigeria's defence in a statement on Thursday refuting the claims.

"For years, Nigeria has supported peace and security of several countries not only in the West African subregion but also on the African continent," the regional bloc said in a statement shared on Thursday.

"Ecowas therefore refutes any suggestion that such a generous and magnanimous country would become a state sponsor of terrorism," it read.

Two weeks ago, Ecowas approved the withdrawal of three military-led countries, including Niger, after they refused to restore democratic rule.

Since the coup, Niger has urged France and other Western powers to withdraw their military bases and formed a security alliance with junta-led neighbours Mali and Burkina Faso.