Investigators from the United Nations are now looking into a potential - the investigators recently said they are "becoming more convinced" that a genocide occurred - genocide in Myanmar that happened between October 2016 and August 2017.
Lee said that Facebook was used as the toll by the state government to disseminate information to the public.
The UN has been denied access to Rahkine since late a year ago, so both Yee and the fact-finding mission have been forced to conduct their investigations in Cox's Bazaar in Bangladesh, where hundreds of thousands of Rohingya are now living in refugee camps.
Backstory: Last August, military forces in Myanmar conducted operations focused on Rohingya Muslims.
Chair of the fact-finding mission, Marzuki Darusman, the former Indonesian attorney general, said the Myanmar government's continued denial of any culpability for the violence in Rahkine was "untenable".
"It [hate speech] has ... substantively contributed to the level of acrimony and dissension and conflict, if you will, within the public", said Darusman, according to The Guardian.More news: Griezmann among goals again as Atletico ease past Celta
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He also said Myanmar would no longer cooperate with Lee because she "has made biased, one-sided and unfair accusations against Myanmar".
United Nations special rapporteur for human rights Yanghee Lee also submitted a report to the Human Rights Council this week, warning that violence against the Rohingya bore "the hallmarks of genocide," and expressing concerns over "high levels of hate speech and incitement to hostility, discrimination and violence, particularly on social media".
Wirathu, a prominent face of Myanmar's Buddhist ultra-nationalist movement, had amassed hundreds of thousands of followers on the network, using it as a platform to attack Muslims, singling out the stateless Rohingya minority. "I'm afraid that Facebook has now turned into a beast, and not what it originally intended".
"This must be aimed at the individuals who gave the orders and carried out violations against individuals and entire ethnic and religious groups", she said. So far, it's estimated that 700,000 Rohingya have fled to Bangladesh as a result.
"The government leadership who did nothing to intervene, stop or condemn these acts must also be held accountable", she added.
Facebook has always been criticised for its role in the Rohingya crisis, an assessment now underscored by comments by United Nations investigators.