Myanmar’s freedom of expression has deteriorated under its new government, a new Human Rights Watch report has said.

It cited the jailing of Reuters reporters Kyaw Soe Oo and Wa Lone, who were investigating the Rohingya crisis, saying the case “shows the military’s willingness to penalise reporters who seek information the military would rather keep hidden”.

The report, Dashed Hopes – The Criminalization of Peaceful Expression in Myanmar, was published on Friday and analyses threats against journalists and activists since the National League for Democracy (NLD) took power in 2016.

Zayar Hlaing, editor of the investigative magazine Mawkun and executive member of the Myanmar Journalist Network, said in the report: “Before the 2015 election, the NLD said it would protect press and promote independent media. After two years, press freedom is worse day by day.”

Linda Lakhdhir, Asia legal adviser at Human Rights Watch and author of the report, said: “Aung San Suu Kyi and the National League for Democracy promised a new Myanmar, but the government still prosecutes peaceful speech and protests and has failed to revise old oppressive laws.”

The rights group said the new government increasingly used section 66(d) of the Telecommunications Law to stifle critical voices through a catch-all definition of “defamation”.

Hunter Marston, a Washington-based independent consultant, agreed with the findings, saying freedom of press had “deteriorated markedly”. In addition to laws being used to suppress criticism, he said the country’s de-facto leader had failed to step up for freedom of expression.

“State Councillor Aung San Suu Kyi has refrained from using her authority to reverse the wrongful charges and imprisonment of Reuters reporters Kyaw Soe Oo and Wa Lone,” he said. “This high-profile case has cast a pall over Myanmar’s journalist community, which continues to brave a repressive political environment to present rigorous news coverage, push back against military atrocities in ethnic minority states, and call attention to a lack of political reforms by the NLD.”

Independent researcher Kim Jolliffe said the intimidations extended much further, with the jailing of Kyaw Soe Oo and Wa Lone “just the most visible tip of the iceberg”.

“Less senior journalists from local publications are regularly being detained without due process or being violently attacked while on the job,” he said. “Numerous journalists, including young women, have been beaten or killed while reporting on commercial ventures or state-linked economic projects in recent years.”

He attributed this to only few of them working for global media corporations and not having high-profile lawyers. In total, Jolliffe said the Assistance Association for Political Prisoners had identified 35 political prisoners who were behind bars, in addition to 56 who were awaiting trial in pre-trial detention and more than 200 outside prison.

NLD spokesman Myo Nyunt could not be reached for comment.