Facebook has been accused of failing to detect and root out hate speech inciting violence and genocide against the Rohingya people, a Muslim minority group in Myanmar.
Campaign group 'Global Witness' says it submitted eight explicit and violent ads containing real examples of Burmese language hate speech against Rohingya.
The group says Facebook approved all eight ads for publishing.
Global Witness removed the ads before they could be published.
Ava Lee, Digital Threats to Democracy Campaign Lead at Global Witness, said: "It is unacceptable that Facebook continues to be shockingly poor at detecting Burmese language hate speech.
"If they still can't do this in Myanmar after five years of supposed efforts, what are the chances that their own voluntary efforts will be enough to avoid contributing to atrocities in Ukraine and other conflict zones," she added.
Meta, Facebook's parent company, says it has built a dedicated team of Burmese speakers, disrupted networks manipulating public debate and taken action on misinformation.
"We've also invested in Burmese-language technology to reduce the prevalence of violating content. This work is guided by feedback from experts, civil society organisations and independent reports, including the UN Fact-Finding Mission on Myanmar’s findings and the independent Human Rights Impact Assessment we commissioned and released in 2018," a Meta spokesperson said.
Dozens of Rohingya refugees in the UK and US have sued Facebook, accusing the social media giant of allowing hate speech against them to spread. They are demanding more than $150bn in compensation.
Sixteen Rohingya youths and women have lodged a complaint against Meta to the OECD National Contact Point in Ireland.
The Facebook whistleblower Frances Haugen has called on Ireland to take action on the OECD complaint.
Ms Haugen is in Ireland this week and is due to speak at Trinity College Dublin today at an event organised by the Technologies, Law and Society Research Group in Trinity’s School of Law and the Schuler Democracy Forum.