Reporters sans frontières, RSF, or Reporters Without Borders, organized the appeal of some 80 people, including media owners and practitioners in francophone Africa.
Since the July 26 coup that overthrew the democratically elected president, foreign and Nigerien reporters have been targeted at demonstrations and faced intimidation and threats.
RSF said attacks on the press have increased.
"From Niamey to Djibouti and from N’Djamena to Antananarivo, journalists and organizations are uniting to call on the Niger junta to respect the fundamental right to reliable and diverse information, and to not hinder the work of news professionals," Sadibou Marong, director of RSF sub-Saharan Bureau, said in a statement.
Radio France Internationale and France 24 TV news have been cut in Niger since Aug. 3.
Both networks had already been suspended in neighboring Burkina Faso and Mali, where coups have also taken place.
Signatories of the appeal include journalists' rights advocates such as the Media Foundation for West Africa, the Federation of African Journalists, the Norbert Zongo Cell for Investigative Journalism in West Africa and news organization Maison de la Presse in Niger.
"We ask the junta to respect the right to information, to pluralism and media independence," said the statement, urging the regime in Niamey to "contribute towards the safety of local and international journalists."
The statement also called for the respect of legal provisions protecting media.
"We call on the CNSP to commit publicly to not invoke against journalists, because of their journalistic work, laws on treason, terrorism and state security," it said.
Friday's appeal was also addressed "to the other Sahel states led by the military."
"We remind them of their duty to respect the rights of journalists and particularly of access to information in the interest of the peoples of the Sahel," it said.Other signatories included the Committee to Protect Journalists and South Africa National Editors Forum.
Journalists based in countries across Africa including Burkina Faso, Burundi, Ghana, Mali, South Sudan, Malawi and others also endorsed the appeal.
Some information for this report came from AFP.
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