Serbian authorities installed spyware on the phones of dozens of journalists and activists, Amnesty International said in a report on Monday.

In the document entitled “A Digital Prison: Surveillance and the suppression of civil society in Serbia,” the non-governmental organization cited digital forensic evidence and testimonies from activists who said they were hacked in recent months. This news comes as the Serbian government has allegedly been suppressing civil society, journalists, and environmental activists in response to growing anti-government sentiment, which recently has manifested in mass protests.

According to the data presented in the report, the software was in most cases installed during police interrogations, arrest, or even informal conversations when the smart phones of the surveilled were confiscated. Serbian authorities allegedly used technologically advanced commercial spyware, such as Pegasus and Cellebrite UFED, which are specifically developed for law enforcement agencies to extract data from phones by circumventing passcodes.

However, authorities allegedly also employed a previously unknown software called NoviSpy, which might be home-grown and can be used to extract sensitive data as well as to remote-control the microphone and camera on many Android devices. While the Serbian government has not responded to the findings of the research, Cellebrite vowed to investigate any use that would be violating human rights.

While spyware is commonly developed for law enforcement to monitor organized crime, it has been increasingly used by governments worldwide to spy on their critics. In the EU, Hungary and Poland have both been accused of purchasing and using this software to spy on journalists and activists. Under European Human Rights Law, every interference with the fundamental right to privacy that is not necessary and proportionate is illegal, especially when it comes to sensitive data detailing personal information.