The outgoing UN human rights chief says Myanmar's de-facto leader Aung San Suu Kyi should have resigned over the military's violent campaign against the Rohingya Muslim minority last year.
Zeid Ra'ad al Hussein told the BBC the Nobel Peace prize winner's attempts to excuse it were "deeply regrettable".
His comments come after a UN report said Myanmar's military leaders should be prosecuted for possible genocide.
Myanmar rejected this, saying it had no tolerance for human rights violations.
The army of the Buddhist-majority nation - which has been accused of systematic ethnic cleansing - has previously cleared itself of wrongdoing.
The UN report, published on Monday, blamed Suu Kyi, a long-term leader of the pro-democracy movement, for failing to prevent the violence.
"She was in a position to do something," Hussein said in an interview with the BBC's Imogen Foulkes. "She could have stayed quiet - or even better, she could have resigned."
"There was no need for her to be the spokesperson of the Burmese military. She didn't have to say this was an iceberg of misinformation. These were fabrications," he said.
"She could have said look, you know, I am prepared to be the nominal leader of the country but not under these conditions."
On Wednesday, the Nobel committee said Suu Kyi could not be stripped of the Peace Prize she was awarded in 1991.
In 2015, her National League for Democracy party won a landslide election victory and she became the country's de-facto leader.
As the Rohingya crisis continued, Suu Kyi's comments on the situation tended to play it down or suggest that people were exaggerating the severity of the violence.
The last time she spoke to the BBC in April 2017, she said: "I don't think there is ethnic cleansing going on. I think ethnic cleansing is too strong an expression to use for what is happening."
Since an outbreak of violence started in August 2017, Suu Kyi has missed several opportunities to speak publicly about the issue, including the UN General Assembly in New York last September.
She later claimed the crisis was being distorted by a "huge iceberg of misinformation" - but then also said she felt "deeply" for the suffering of "all people" in the conflict.
Myanmar, she said, was "committed to a sustainable solution... for all communities in this state."
What is the Rohingya crisis?
The Rohingya are a Muslim minority in Myanmar, where they are denied citizenship and considered illegal immigrants from Bangladesh despite calling the Rakhine state home for generations.
The military launched a crackdown in Rakhine last year after Rohingya militants carried out deadly attacks on police posts.
Thousands of people have died and more than 700,000 Rohingya have fled to neighbouring Bangladesh since August 2017.
There have also been widespread allegations of human rights abuses against the persecuted group, including arbitrary killing, rape and burning of land over many years.