Michelle Bachelet in a statement on Monday in the Swiss city of Geneva said that she was "shocked" by Myanmar's jailing of the two journalists for seven years and called for their immediate release.
She stressed that their trial was "travesty of justice". "The trial was a travesty of justice, so I will urge the Myanmar government to release them as soon as possible, immediately."
"Their conviction follow[s] a legal process that clearly breached international standards," the former Chilean president said on her first day as UN High Commissioner for Human Rights, Presstv Reprted.
"It sends a message to all journalists in Myanmar that they cannot operate fearlessly, but must rather make a choice to either self-censor or risk prosecution," she noted
Elsewhere in her statement, she also urged Myanmar to free all other journalists detained for exercising their freedom of expression.
Journalists Wa Lone, 32, and Kyaw Soe Oo, 28, were detained in December last year after reporting on the killings of 10 Rohingya Muslims by the Myanmar military in the northwestern state of Rakhine.
Judge Ye Lwin convicted the journalists on Monday of being guilty for breaching a law on state secrets when they collected and obtained confidential documents.
The court’s ruling on Monday prompted reaction from the United Nations, the European Union, the US, Human Rights Watch as well as press freedom advocates, who have long been calling for the reporters’ release.
Separately, UN Resident and Humanitarian Coordinator in Myanmar Knut Ostby earlier said that the two journalists should be released.
"Wa Lone and Kyaw Soe Oo should be allowed to return to their families and continue their work as journalists," Ostby said, adding, “We continue to call for their release."
Britain has also called for the "immediate" release of the journalists, saying the verdict had "undermined freedom of the media."
"We are extremely disappointed with this verdict and sentencing and we call for the journalists to be released immediately," a spokesman for British Prime Minister Theresa May said.
Britain's Minister for Asia and the Pacific Mark Field said in a statement that he was "extremely disappointed" by the verdict, calling it a "bad day" for Myanmar.
"They provided valuable reporting on abhorrent human rights violations in Rakhine state, and I have consistently called for their immediate release, including directly with the Burmese (Myanmarese) government," the minister said.
"Journalists must be free to carry out their jobs without fear or intimidation," he added.
Myanmar’s government has been under intense pressure over the violent military crackdown on the Muslim community, which has forced more than 700,000 Rohingya to flee to neighboring Bangladesh.
The UN has described the clampdown campaign -- which has seen random killings, gang rapes and arson attacks -- as the “textbook example of ethnic cleansing.”
The world body’s Independent International Fact-Finding Mission on Myanmar said in a report last week that the country’s commander-in-chief and other generals should stand trial for “genocide” and war crimes against the Rohingya minority group.
The mission has also said the de facto leader Aung San Suu Kyi should have resigned over her silence on the campaign of terror.