Facebook parent Meta Platforms deliberately engineered its social platforms to hook kids and knew — but never disclosed — that it had received millions of complaints about underage users on Instagram but only disabled a fraction of those accounts, according to a newly unsealed legal complaint described in reports from The Wall Street Journal and The New York Times.

The complaint, originally made public in redacted form, was the opening salvo in a lawsuit filed in late October by the attorneys general of 33 states.

According to the reports, Meta said in a statement that the complaint misrepresents its work over the past decade to make the online experience safe for teens and said it doesn't design its products to be addictive to younger users.

Meta didn't immediately provide a comment on the unredacted complaint following a request from The Associated Press.

Company documents cited in the complaint described several Meta officials acknowledging that the company designed its products to exploit shortcomings in youthful psychology such as impulsive behaviour, susceptibility to peer pressure and the underestimation of risks, according to the reports.

Others acknowledged that Facebook and Instagram were also popular with children under age 13, who, per company policy, were not allowed to use the service.

One Facebook safety executive alluded to the possibility that cracking down on younger users might hurt the company's business in a 2019 email, according to the Journal report. But a year later the same executive expressed frustration that while Facebook readily studied the usage of underage users for business reasons, it didn't show the same enthusiasm for ways to identify younger kids and remove them from its platforms.

The complaint noted that at times Meta has a backlog of up to 2.5 million accounts of younger children awaiting action, according to the reports.