A Canadian data analytics expert says he wanted to expose a "problematic" invasion of privacy when he sounded the alarm and alleged a data company he helped found misused personal information from millions of Facebook users while working for Donald Trump's 2016 U.S. presidential campaign.

In an interview with The National's Adrienne Arsenault, Christopher Wylie said he was tasked with "psychological profiling" while working at Cambridge Analytica and was able to pull data from users through apps that required the use of Facebook.

"They would fill out psychological surveys and then that app would then go and pull all of their Facebook data," said the 28-year-old from B.C.

Cambridge Analytica says it has up to 5,000 data points on 230 million American voters. Now one of those voters is getting ready to sue the company to find out what it knows about him. 9:07

"From that, we were able to make inferences or predictions about people who we haven't yet spoken to," Wylie added.

"It allowed us to profile upwards of 50 million Americans over a span of a couple of months and understand not only their personality traits but how they think... and what exactly we need to do in order to pick at certain mental or emotional vulnerabilities so that those people would behave in a particular way that was conducive to [Trump campaign chief executive] Steve Bannon's objective."

'I need to speak out'

Wylie said he decided to go the press with his story — first reported by The New York Times and The Observer of London — after seeing Trump become president and the rise of the alt-right.

"It really made me reflect on the impact that Cambridge Analytica has had," he said.

"I reflected on it... I said to myself that I need to speak out now because I have seen the impact that this company has had and I think people should know about how it works."

Wylie also said the company's practices were unethical and needed to be called out.

"I think that the algorithms that they have built... using that private data they acquired without consent, is problematic."

In a statement on Saturday, Cambridge Analytica said it "fully complies with Facebook's terms of services," adding that they "do not hold or use any data from profiles."

Cambridge Analytica fully complies with Facebook’s terms of service. We are in touch with Facebook now and can confirm that we do not hold or use any data from profiles <a href="https://t.co/YD8kFXCFTL">https://t.co/YD8kFXCFTL</a> —@CamAnalytica

On Sunday, Facebook said it was was conducting a "comprehensive internal and external review" to determine if the personal data of 50 million users that was reported to be misused still existed.

Paul Grewal, a Facebook vice-president and deputy general counsel, said in a statement on Sunday the company was committed to "vigorously enforcing our policies to protect people's information."