The world's largest social media company Facebook suffered the biggest one-day drop of its stocks by seven percent on Wall Street Monday in four years following reported data leakage of its 50 million users for alleged political purposes, the Associated Press (AP) reported.

The Facebook loss came after U.S. and British media reported that the data of more than 50 million Facebook users were inappropriately used by a British data analysis company, Cambridge Analytica, in activities allegedly connected with U.S. President Donald Trump during his 2016 campaign.

Trump's campaign reportedly used the firm's data during the primaries but not during the general election, and Federal Election Commission numbers showed the firm collected 5.9 million U.S. dollars in 2016 from Trump's campaign, California-based The Mercury News daily reported Monday.

The AP quoted Facebook as saying last week that Cambridge Analytica received user data from a Facebook app years ago that purported to be a psychological research tool, though the firm wasn't authorized to have that information.

Facebook admitted that an estimated 270,000 people had downloaded the app and shared their personal details with it.

Last Friday, Facebook said in an official post that it had suspended "Strategic Communication Laboratories (SCL), including their political data analytics firm, Cambridge Analytica," from its website.

It said the two companies had failed to delete user data acquired in 2015 in violation of Facebook rules.

Last Saturday, Facebook said that claim that this is a data breach is completely false, arguing that people knowingly provided their information.

"No systems were infiltrated, and no passwords or sensitive pieces of information were stolen or hacked," Facebook said in its official blog post.

Mercury News said Monday that a U.S. senator is demanding that Facebook CEO Mark Zuckerberg testify before the Senate Judiciary Committee on the abuse of user data for U.S. campaign activities.