A Facebook whistle-blower has said the social media giant's practices amplified “extremism and polarisation”.
Frances Haugen, a former Facebook engineer, told a European Parliament committee that the EU could set the global “gold standard” on clamping down on the power of large technology corporations.
Ms Haugen insisted that the social media platform put more priority on profit than on curtailing toxic content.
Facebook has said Ms Haugen's allegations distort reality and called her a mid-level engineer with limited access to important decisions.
“I saw that Facebook repeatedly encountered conflicts between its own profits and our safety,” she said.
“Facebook consistently resolved these conflicts in favour of its own profits. The result has been a system that amplifies division, extremism and polarisation.
"It undermines societies around the world. In some cases, this dangerous online talk has led to actual violence that harms and even kills people.”
The EU is pushing through new laws that could force the world's biggest tech firms to rethink the way they do business.
Ms Haugen endorsed the plans, especially the Digital Services Act, which would create much stricter oversight of harmful and illegal content on platforms such as Facebook, which also owns Instagram.
“Facebook chooses profit over safety every day and without bold action from lawmakers this will continue,” she told members.
“Facebook has exploited its ability to hide the actual behaviour of the platform to allow our safety to decay to an unacceptable level.
“If Facebook is allowed to continue to operate in darkness we'll only see escalating tragedies as a result. I came forward at great personal risk because I believe we still have time to act, but we must act now.”
Ms Haugen said she believed “that Facebook's products harm children, stoke division, weaken our democracy and much more.
“The company's leadership knows ways to make Facebook and Instagram safer, but they won't make the necessary changes because they have put their immense profits before people.
"The consequences are severe.”