With UK officials just having raided Cambridge Analytica's London HQ amid allegations the firm illegally acquired Facebook data, a fresh report has claimed that the social network was warned user data was at risk as early as 2011.
According to an investigation by the Telegraph the tech giant's European regulator - the Irish Data Protection Commissioner (DPC) warned the business seven years ago that it was failing to ensure that data was protected when it was passed on to third-party software and app developers.
Following the caution, Facebook updated the way users were notified about how apps gleaned data, but did not fully block the practice of gathering data from users based on their 'friends' interactions with third-party apps until 2015.
It was in 2013 that academic Dr Aleksandr Kogan is alleged to have used a quiz app to harvest the data of 50 million users, before passing it on to Cambridge Analytica.
While both parties have denied explicit wrongdoing, Facebook and Cambridge Analytica are facing whistleblower claims this data was used to support Donald Trump's 2016 presidential election campaign, with the latter firm also being said to have yielded influence over other democratic votes including the EU referendum.
On Sunday (25 March), a statement of apology from Facebook founder and chief executive Mark Zuckerberg appeared in a number of UK newspapers in the form of a full page print ad. The Observer, which broke the story, notably carried the ad in this week's edition, as did the Sunday Times.
In a statement addressing the DPC's 2011 audit, a Facebook spokesperson said: "Third-party apps built on Facebook was the subject of detailed examination … by the Irish Data Protection Commissioner in 2011-2012. In September 2012, they acknowledged the progress we had made and in 2014 we announced we were changing the entire platform.”
The latest revelation, and investment in print ads, comes after the stormiest week in Facebook's 14-year history; which has included the rise of a #DeleteFacebook campaign online supported by the likes of Elon Musk and WhatsApp founder Brian Action who sold his company to Facebook for $19bn in 2014.
Zuckerberg took five days to publicly address the situation after the Observer broke the story last Saturday (17 March). He explained how the "way Facebook worked at the time" had allowed Kogan to access tens of millions users' data.
He added: "We have a responsibility to protect your data, and if we can't then we don't deserve to serve you. I've been working to understand exactly what happened and how to make sure this doesn't happen again."
The boss has called on by a parliamentary committee to give evidence about the scandal in the UK. In the US, meanwhile, the company has drawn scrutiny from the Federal Trade Comission (FTC).
Over the weekend, enforcement officers from the UK's Information Commissioner (ICO) spent close to seven hours searching Cambridge Analytica's central London premises.