WASHINGTON-- The U.S. Federal Trade Commission said on Tuesday it had referred a complaint against the social media platform TikTok and its parent company ByteDance over potential violations children's privacy to the Justice Department. In March, a source told Reuters the FTC could resolve a probe into TikTok over allegedly faulty privacy and data security practices by either filing suit or reaching a settlement. "The investigation uncovered reason to believe named defendants are violating or are about to violate the law and that a proceeding is in the public interest, so the Commission has voted to refer a complaint to the Department of Justice," the FTC said in a statement. Reuters in 2020 first reported the FTC and the U.S. Justice Department were looking into allegations the popular social media app failed to live up to a 2019 agreement aimed at protecting children's privacy. "Although the Commission does not typically make public the fact that it has referred a complaint, we have determined that doing so here is in the public interest," the statement continued, without giving details. TikTok said Tuesday it has been working with the FTC for more than a year to address the agency's concerns. "We're disappointed the agency is pursuing litigation instead of continuing to work with us on a reasonable solution," TikTok said. "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." The probe is separate from ongoing concerns in Congress about the potential that the data of TikTok's 170 million U.S. users could be improperly accessed by the Chinese government. TikTok denies the allegation. TikTok is set on Thursday to file its legal brief in its lawsuit challenging a law passed in April that requires its Chinese-parent ByteDance to divest TikTok's U.S. assets by Jan. 19 or face a ban.