The Government has warned Facebook ministers are prepared to bring in new tough regulations unless it reforms in the wake of the Cambridge Analytica scandal.
At talks with senior Facebook executives in London, Culture Secretary Matt Hancock made clear its current data practices were "nowhere near" where they should be and that wholesale change was needed.
He was said to have told US-based vice president of global policy management Monika Bickert, and global deputy chief privacy officer Stephen Deadman the Government would "hold their feet to the fire" until they addressed a "spectrum of issues" where they fell short.
The talks took place as Facebook founder Mark Zuckerberg was giving evidence for a second day to US lawmakers in Washington.
In a statement following the meeting, described as "robust but constructive", Mr Hancock said: "Social media companies are not above the law and will not be allowed to shirk their responsibilities to our citizens.
"We will do what is needed to ensure that people's data is protected and don't rule anything out - that includes further regulation in the future."
According to officials, Mr Hancock sought assurances UK citizens' data was no longer at risk and that they would be given more control over their data in future - including making it easier to transfer their data to other platforms if they chose.
While he acknowledged that good progress had been made in some areas - such as the removal of terrorist content - he was said to have made clear that Facebook still needed to be less invasive, more transparent and ensure control of data sat with users rather than the platform.