The two reporters were working on stories about the crackdown on members of the Rohingya minority, who have been the target of a sustained campaign of aggression by the Myanmar army.

US Embassy: 'Deep concern'

The US Embassy in Yangon said Wednesday the US was "deeply concerned" over the "highly irregular" arrest of the two journalists.

"For a democracy to succeed, journalists need to be able to do their jobs freely. We urge the government to explain these arrests and allow immediate access to the journalists," a statement said.

Reuters President and Editor-in-Chief Stephen Adler called for their immediate release. He said they were "reporting on events of global importance" and were taken into custody during the course of that work.

"We are outraged by this blatant attack on press freedom," Adler said in a statement.

Wa Lone has worked for Reuters since last year and has covered a range of stories, including the Rohingya crisis in Rakhine state, according to the news agency. Kyaw Soe Oo joined Reuters in September.

Harsh responses

Crackdown on dissent in Myanmar, also known as Burma, remains harsh, with an anti-defamation clause in the country's telecommunications law often used to quash opposition voices.

Nobel Prize-winner Aung San Suu Kyi, the country's de facto leader, has come under intense criticism for her government's handling of the Rohingya crisis.

Myanmar's military says it has been targeting terrorists who carried out a series of deadly attacks on security forces. While the Nobel laureate leads the country in a power-sharing agreement with the military, she has little, if any, control over the country's armed forces.

In a speech in September, Suu Kyi said she is aware of the "world's attention" focused on Myanmar, but said her government "does not fear international scrutiny."

"If you are interested in joining us in our endeavors, please let us know," she added. "We can arrange for you to visit these areas and to ask (those who have stayed) why they have not fled, why they have chosen to remain in their villages."

Access to Rakhine State has been heavily restricted to media, human rights groups, and diplomats.

Worldwide attacks on the press

The most common reasons journalists are put behind bars around the world include "anti-state charges" and "broad and vague terror laws," according to the CPJ report.

Turkey has imprisoned the highest number of reporters at 73. China is second with 41.

The report had harsh words for US President Donald Trump, whose attacks on the press have led to a climate of distrust for the media.

"President Donald Trump's nationalistic rhetoric, fixation on Islamic extremism, and insistence on labeling critical media 'fake news' serves to reinforce the framework of accusations and legal charges that allow [some foreign] leaders to preside over the jailing of journalists," the report states.