The United Nations human rights chief said that social media, including Facebook, must proactively block content inciting hatred and prevent online campaigns which target minorities, such as those undertaken in Myanmar

Zeid Ra’ad al-Hussein, U.N. High Commissioner for Human Rights, was speaking after U.N. experts accused Myanmar generals of “genocidal intent” and said Facebook had allowed its platform to be used to incite violence against Rohingya.

Facebook had already taken action on the pages of Myanmar military officials . It removed the accounts of Myanmar military officials from the social media website and an Instagram account to prevent the spread of “hate and misinformation” after reviewing the content.

Zeid, whose spokesman said he has met with major tech companies in Silicon Valley, including Facebook and Google, in recent months, was speaking to a news conference before his four-year term ends on Aug. 31. Zeid said he didn’t feel Facebook took the issue seriously at first but that the company’s attitude began to change after Yanghee Lee, U.N. special rapporteur on human rights in Myanmar, told a Geneva press conference in March that Facebook was being used in the country to spread hate speech.

The Chief felt that Facebook should have taken action well in advance and should not wait for the authorities or media to point out the issue. Facebook should have certain policies to cope up with situations like this.

Facebook said that while it was too slow to act in the case of Myanmar, it was now making progress, with better technology to identify hate speech and improved reporting tools. However, Zeid said there was a danger that social media could be over-regulated in a way that breaches human rights law including the right to freedom of expression.

U.S. President Donald Trump on Tuesday accused Google’s search engine of promoting negative news articles and hiding “fair media” coverage of him, vowing to address the situation without providing evidence or giving details of action he might take. Trump’s attack against the Alphabet Inc unit follows a string of grievances against technology companies, including Twitter Inc and Facebook, which he has accused of silencing conservative voices.