Niger's coup leaders have accused the head of the United Nations of obstructing their participation in the body's General Assembly, saying it was "likely to undermine any effort to end the crisis in our country".
Rebel elite soldiers overthrew president Mohamed Bazoum on July 26 and have since detained him at home with his family.
Negotiations to restore civilian rule have yet to bear fruit, with the junta demanding a three-year transition and the Economic Community of West African States (ECOWAS) calling for the immediate return of the democratically elected Bazoum.
The coup has also been strongly criticised by Western governments and global bodies such as the UN, which is holding its General Assembly of world leaders in New York this week.
In a news release read on public television on Friday night, the military said UN Secretary-General Antonio Guterres "went astray in the exercise of his mission by obstructing Niger's full participation in the 78th session of the UN General Assembly."
Credentials questions
It criticised "the perfidious actions" of the UN leader, adding that they were "likely to undermine any effort to end the crisis in our country".
Bakary Yaou Sangare, who before the coup was Niger's ambassador to the UN and is now its foreign minister, was the new leaders' chosen representative for the gathering.
But, according to a diplomatic source, there was also an application by the overthrown government to represent Niamey, AFP news agency reports.
"In case of competing credentials from a Member State the secretary-general defers the matter to the Credentials Committee of the General Assembly who will deliberate on the matter," Guterres' spokesman Stephane Dujarric said.
"The secretary-general does not decide." Because the committee will not meet until later, no representative from Niger was added to the speakers' list.
Niger "forcefully rejects and denounces this clear interference by Mr Guterres in the internal affairs of a sovereign state", the junta said.
Sahel Alliance
One of the world's poorest nations, Niger is the fourth country in West Africa to suffer a coup since 2020, following Burkina Faso, Guinea and Mali.
Bazoum's removal heightened international worries over the Sahel region, which faces growing insurgencies linked to Al-Qaeda and the so-called Islamic State group.
Regional sanctions since the coup mean food and medicines are scarce in Niger, prices are skyrocketing and there are blackouts after Nigeria cut electricity supplies.
West African regional leaders who had threatened to use force to reverse the coup, say they are now negotiating with the junta for a diplomatic solution.
The military leaders of Mali, Burkina Faso and Niger signed a mutual defence pact this month, saying they aimed to "establish an architecture of collective defence and mutual assistance for the benefit of our populations".
