The U.N. has put blame on Facebook for playing a role in spreading hate speech amid the mounting Rohingya crisis in Myanmar. Marzuki Darusman, who leads the U.N. Fact-Finding Mission on Myanmar, said Monday that social media played a "determining role" in the crisis.

"It has substantively contributed to the level of acrimony and dissension and conflict, if you will, within the public. Hate speech is certainly of course a part of that. As far as the Myanmar situation is concerned, social media is Facebook, and Facebook is social media," Darusman said, according to Reuters news agency.

The U.N. Human Rights Council heard two reports on the crisis Monday: One from Darusman and one from U.N. Special Rapporteur on Human Rights in Myanmar Yanghee Lee.

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"We know that the ultranationalist Buddhists have their own [Facebook pages] and really [are] inciting a lot of violence and a lot of hatred against the Rohingya or other ethnic minorities," Lee said. "And I'm afraid that Facebook has now turned into a beast, [instead of] what it was originally intended to be used [for] -- maybe in other parts of the world too."

Facebook said in a statement there is "is no place for hate speech or content that promotes violence" on its platform, and added that it has "worked with experts in Myanmar for several years to develop safety resources and counter-speech campaigns."

David Mathieson, an independent analyst who's lived and worked in the region for years, told CBS News he thinks social media has been "one of the most damaging aspects of this entire crisis."

"I think people internationally need to realize that five years ago, it cost a couple hundred dollars to get a sim card. Not many people had phones," Mathieson said in February.

"What we've seen in the past three or four years is this country getting online, everyone having a cheap smartphone and access to Facebook," he explained. "And so there's not the media literacy. There's not the kind of ability to understand this medium, and the limitations of online speech."

Meanwhile, Myanmar's government on Tuesday rejected the reports presented to the U.N. Human Rights Council that concluded it committed extreme human rights violations, probably amounting to crimes under international law, in its repression of several minority groups.

Government spokesman Zaw Htay said the reports lacked credibility. The report of the Fact-Finding Mission, chaired by former Indonesian Attorney-General Marzuki Darusman, was based on hundreds of accounts by victims and witnesses of reported human rights violations, as well as satellite imagery, photographs and video footage.

The mission's members were barred by Myanmar's government from entering the country, so its researchers interviewed refugees and others in Bangladesh, Malaysia and Thailand.

Zaw Htay said Buddhist-majority Myanmar had barred the Fact-Finding Mission because it rejected its legitimacy. He questioned the reliability of its research and cast doubts on the credibility of the refugees' stories.

"We are not denying rights violations but we are asking for strong, fact-based, and trustworthy evidence on the allegations they are making," Zaw Htay told The Associated Press by telephone.

He also said Myanmar would no longer cooperate with Lee because she "has made biased, one-sided and unfair accusations against Myanmar."

Lee told the Human Rights Council that violent sweeps by the Myanmar army in Rakhine state that prompted about 700,000 Rohingya Muslims to flee to neighboring Bangladesh "bear the hallmarks of genocide."

She said accountability for the abuses in Rakhine should be "the focus of the international community's efforts to bring long-lasting peace, stability and democratization to Myanmar."

"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. "The government leadership who did nothing to intervene, stop, or condemn these acts must also be held accountable."

The situations in Kachin and Shan states, which involve actual combat between government soldiers and ethnic rebel groups seeking greater autonomy, have received much less international attention than the plight of the Rohingya.