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Facebook and the Federal Trade Commission are negotiating a multibillion-dollar fine to settle an investigation into the social network's privacy practices, The Washington Post reported Thursday.

It'd be the largest fine ever imposed by the agency, according to the Post, though the exact amount hasn't yet been determined. Facebook was initially concerned with the FTC's demands, a person familiar with the matter told the publication. If the two parties don't come to an agreement, the FTC could reportedly take legal action.

A Facebook representative said the company isn't commenting on the Post report, but added: "We are cooperating with officials in the US, UK, and beyond. We've provided public testimony, answered questions, and pledged to continue our assistance as their work continues."

The FTC declined to comment.

The FTC began investigating Facebook last year after it was revealed that Cambridge Analytica, a digital consultancy linked to the Trump presidential campaign, improperly accessed data from as many as 87 million Facebook users. The agency is looking into whether Facebook's actions violated a 2011 agreement with the government in which it pledged to improve its privacy practices. Facebook has said it didn't violate the consent decree.

Under the agreement, Facebook agreed to get permission from users before sharing their data with third parties. In addition, the tech giant is required to have a third party conduct audits every two years for the next 20 years to ensure the program is effective.

Facebook reportedly could reach a deal with the government by agreeing to pay a fine and altering some of its business practices. A judge would have to approve the settlement, according to the Post. The FTC could impose new rules forcing Facebook to go through more stringent, regular checkups to ensure it's in compliance with the settlement, people familiar with the matter told the Post. Alternatively, the tech giant could reportedly opt to challenge the FTC over its findings and suggested penalties.

The FTC's last record-setting fine against a tech company for breaking a privacy agreement was reportedly against Google in 2012, for $22.5 million.

First published Feb. 14, 3:08 p.m. PT.

Update, 3:27 p.m.: Adds details throughout.

Update, Feb. 19 at 3:38 p.m.: Adds that the FTC declined to comment.