Amnesty International on Monday said journalists in Nigeria are operating under a "climate of fear", after 19 reporters were detained by security forces this year.
The rights group said there has been a disturbing rise in threats and attacks on journalists for expressing critical views of the authorities on both conventional and social media in the country.
"Increasingly, the human rights cost of receiving and sharing information for journalists, bloggers and activists comes with dangerous consequences, forcing journalists, bloggers and activists to operate in a climate of fear," Amnesty's Nigeria director Osai Ojigho said in a statement.
"Journalists, bloggers and activists are facing increased risks simply for publishing articles and demanding accountability from the authorities. This is totally unacceptable. The authorities must immediately put an end to this hostility towards human rights."
Amnesty accused the police, military and the Department of State Services (DSS) secret police of being responsible for the clampdown on press freedom in Nigeria.
It cited the case of Abiri Jones, the publisher of Weekly Source who was arrested in 2016 and detained without access to family or lawyers for two years by the DSS.
"He was released on 15 August 2018 and rearrested on 20 May 2019 before being put on trial for terrorism and cybercrimes charges," it added.
Some of the other journalists mentioned in the report said that they had been beaten and "tortured" during interrogations.
In January the Nigerian security forces raided the offices of prominent newspaper Daily Trust over its coverage of the Boko Haram insurgency in the northeast of the country.
Local and international rights bodies have frequently accused Nigeria's security forces of abuses, including arbitrary arrests and extra-judicial executions.
The authorities have consistently denied the allegations.