The latest federal class action to hit Facebook Inc. on Tuesday accused the social media giant of violating privacy laws in allowing Cambridge Analytica to access personal information of 87 million users.

The complaint, filed in the U.S. District Court for the District of Delaware, joined a series of cases across the country that stem from the unfolding Cambridge Analytica debacle, and it came just hours before Facebook CEO Mark Zuckerberg began to testify before two Senate committees about online data privacy and other issues.

According to the Delaware lawsuit, Facebook knew about problems with its platform in 2011, but failed to close a “back door” that allowed outside app developers to obtain “wide-scale, unauthorized access” to the names,  addresses, telephone numbers and locations of tens of millions of Facebook users.

“Facebook has made billions of dollars selling advertisements targeted to its customers, and in this instance made millions selling advertisements to political campaigns that developed those very ads on the back of their customers' own stolen personal information,” Richard W. Fields, one of the attorneys for the plaintiffs, said in a statement. “That's unacceptable, and they must be held accountable.”

The lawsuit also names Cambridge Analytica, a New York-based political consulting firm with ties to President Donald Trump's 2016 campaign, as well as other companies that supposedly played a role in the breach.

Facebook did not respond Tuesday to an email seeking comment on the lawsuit. An automated response from Cambridge Analytica's press office directed reporters to the firm's official Twitter feed. The company did not provide a comment on Tuesday.

According to the 42-page complaint, a 2011 investigation by the Federal Trade Commission revealed that Facebook's privacy settings were ineffective in stopping third parties from accessing users' personal information either directly or through a Facebook friend who authorized a platform app, like an online personality quiz, in violation of its privacy policy.

“Despite this knowledge and its obligations to its users, Facebook took no affirmative action, and, thereby, refused or otherwise failed to fix, change or otherwise remedy this known defect in its existing developer tools,” the complaint said.

The oversight allowed Aleksandr Kogan, a professor at Cambridge University, in 2014 to obtain user data through the online personality-test app thisisyourdigitallife, and then improperly share it with Cambridge Analytica, which had been hired by the Trump campaign, according to the filing.

At the time, Steve Bannon, a former high-level adviser to Trump, was serving as a “top executive of Cambridge Analytica” and “was deeply involved in the company's strategy,” according to media reports cited in the complaint.

Bannon is not a named defendant in the case. But the complaint did name Kogan and his company, Global Science Research as defendants. Another firm, SCL Elections, was accused of improperly licensing the information to Cambridge Analytica.

In the document, the plaintiffs said that Facebook learned about the breach in December 2015, but did not take action until the following October, when media reports began to surface.

While Zuckerberg has publicly apologized for Facebook's role in the scandal, the company's lawyers have argued in court papers that “Facebook broke no laws and violated no legal duties.”

Cambridge Analytica said in a series of tweets on Tuesday that it never used the data on the Trump campaign and that it deleted all of the information it obtained from Global Science Research once Facebook said that its terms of service had been broken.

The U.S. Judicial Panel on Multidistrict Litigation is currently considering whether to coordinate about 20 consumer cases against Facebook and Cambridge Analytica in an MDL in California federal court.

The plaintiffs in the Delaware case are seven Facebook users in the United States and England who said their personal information had been compromised. They are represented by Fields of Fields PLLC in Washington; Robert F. Ruyak, Korula T. Cherian, Richard Ripley and Rebecca Anzidei of Ruyak Cherian, also in Washington; Christopher P. Simon and David Holmes of Cross & Simon in Wilmington; and Matthew Jury of McCue & Partners in London.

The case is captioned Redmond v. Facebook.