New York, New York - The Federal Trade Commission (FTC) announced Tuesday that it had referred a complaint against TikTok to the Justice Department, saying the popular video sharing app may be violating child privacy laws.

The complaint, which also names TikTok's Chinese parent company Bytedance, stems from an investigation launched following a 2019 settlement, the FTC said in a statement.

At the time, the US regulator accused TikTok's predecessor, Musical.ly, of having improperly collected child users' personal data.

TikTok agreed to pay $5.7 million under the settlement and to take actions to come into compliance with the Children's Online Privacy Protection Act (COPPA), a 1998 law.

FTC chair Lina Khan said Tuesday on X that the follow-up investigation had "found reason to believe that TikTok is violating or about to violate" COPPA and other federal laws.

A separate FTC statement said that the public announcement of the referral was atypical, but "we have determined that doing so here is in the public interest."

Neither Khan nor the FTC statement further specified the violations TikTok and Bytedance were believed to have committed.

TikTok said Tuesday on X that it had worked for more than a year with the FTC "to address its concerns" and was "disappointed" the agency was "pursuing litigation instead of continuing to work with us on a reasonable solution."

"We strongly disagree with the FTC's allegations, many of which relate to past events and practices that are factually inaccurate or have been addressed," it said.

"We're proud of and remain deeply committed to the work we've done to protect children, and we will continue to update and improve our product."

The complaint comes a day after Surgeon General Vivek Murthy called for new restrictions on social media to combat a sweeping mental health crisis among young people.

Among the steps proposed by Murthy in his New York Times op-ed was notably a tobacco-style warning label "stating that social media is associated with significant mental health harms for adolescents."

TikTok, with roughly 170 million US users, is facing a possible ban across the US within months as part of legislation signed by President Joe Biden in late April.

The company has filed a lawsuit challenging the constitutionality of the ban, which is working its way through US courts.