Facebook on Friday said it was suspending political data analytics firm Cambridge Analytica, which worked for US President Donald Trump's 2016 election campaign.

Facebook said that it suspended Cambridge Analytica and its parent group Strategic Communication Laboratories (SCL) after receiving reports that they did not delete information about Facebook users that had been inappropriately shared.

Facebook did not mention the Trump campaign or any political campaigns in its statement, which was attributed to company deputy general counsel Paul Grewal.

"We will take legal action if necessary to hold them responsible and accountable for any unlawful behavior," Facebook said, adding that it was continuing to investigate the claims.

Data analytics firm Cambridge Analytica harvested private information from more than 50 million Facebook users in developing techniques to support President Donald Trump's 2016 election campaign, the New York Times and London's Observer reported on Saturday.

On its Web site, Cambridge Analytica says it "provided the Donald J Trump for President campaign with the expertise and insights that helped win the White House."

The Observer said Cambridge Analytica used the data, taken without authorization in early 2014, to build a software program to predict and influence choices at the ballot box.

The New York Times said interviews with a half-dozen former Cambridge Analytica employees and contractors, and a review of the firm's emails and documents, revealed it not only relied on the private Facebook data but still possesses most or all of it.

The Observer said the data was collected through an app called thisisyourdigitallife, built by academic Aleksandr Kogan, separately from his work at Cambridge University.

Through Kogan's company Global Science Research (GSR), in collaboration with Cambridge Analytica, hundreds of thousands of users were paid to take a personality test and agreed to have their data collected for academic use, the Observer said.

However, the app also collected the information of the test-takers' Facebook friends, leading to the accumulation of a data pool tens of millions-strong, the paper said.

Cambridge Analytica combines the analysis of people's personalities with demographics to predict and influence mass behavior, and has data on 220 million people in the US, two-thirds of the country's population.

Trump's campaign hired Cambridge Analytica in June 2016 and paid it more than US$6.2 million, according to Federal Election Commission records.

The suspension of the analytics firm means Cambridge Analytica and SCL cannot buy ads on the world's largest social media network or administer pages belonging to clients, Facebook vice president Andrew Bosworth said in a Twitter post.