A former Facebook employee has told MPs it did not try hard enough to detect when user data was taken or misused by apps built for the site.
The tech giant employed Sandy Parakilas in a role focused on data protection and app compliance, in 2011 and 2012.
He told the Digital, Culture, Media and Sport Committee Facebook had "lost sight" of what had happened to user data once it had left the company.
He confirmed it was possible to target ads based on users' political views.
For example, an anti-Islamic group such as Britain First could target people with similar opinions, Mr Parakilas told the committee.
He also said he had made Facebook executives aware of his concerns at the time.
Mr Parakilas's hearing follow reports that Facebook user data was allegedly acquired illicitly and passed to Cambridge Analytica, a data analytics and advertising company, in 2014.
The app that acquired this data was developed privately by a Cambridge University researcher, Dr Aleksandr Kogan.
Mr Parakilas told the MPs the system through which apps could access data had been "far outside the boundaries of what should have been allowed".
"Facebook was allowing developers to access the data of people who hadn't explicitly authorised that," he said.
Mr Parakilas also suggested that Facebook, keen to grow as quickly as possible, had been willing to take the "risk" of allowing "unvetted" people to access its data.
When asked if Facebook had treated data like a "Wild West frontier", by Conservative MP Julian Knight, Mr Parakilas agreed it had.
And when Labour MP Julie Elliott asked whether this situation had posed a challenge to democracy, Mr Parakilas agreed, saying it had posed a "huge challenge" to democracy.