Lawmakers ask F.T.C. chair to investigate TikTok’s data practices.

The leaders of the Senate Intelligence Committee asked the Federal Trade Commission on Tuesday to investigate whether TikTok, the Chinese-owned video app, had misled the public about whether Beijing could have access to American user data.

In a letter to Lina Khan, the chair of the F.T.C., Senator Mark Warner of Virginia, a Democrat who heads the Intelligence Committee, and Senator Marco Rubio of Florida, the panel’s top Republican, said they were concerned about recent reports that TikTok’s user data was accessible to employees of its parent company, ByteDance, in China. They also said they were worried that ByteDance was more involved in TikTok’s decision making than the app had claimed in the past.

“In light of repeated misrepresentations by TikTok concerning its data security, data processing and corporate governance practices, we urge you to act promptly on this matter,” the lawmakers said.

A spokesman for the F.T.C. did not immediately respond to a request for comment. The F.T.C. has the authority to investigate instances in which companies make deceptive claims about their practices. The agency reached an agreement with TikTok in 2019 to settle accusations that an earlier iteration of the app had wrongly collected children’s personal data.

For years, TikTok has faced questions from U.S. officials about whether it poses a national security threat because a Chinese company owns it. In 2020, President Donald J. Trump cited those security concerns and demanded that the video app be sold if it was to remain in U.S. app stores. He later announced a potential deal in which ByteDance would sell at least part of TikTok to Oracle, a U.S. tech company, though the transaction never came to fruition.

Those questions tailed off after Mr. Trump left office, but have recently come to the fore again. Last month, BuzzFeed News reported that ByteDance employees in China had gained access to the app’s U.S. data as recently as this year and that employees were struggling to cordon off information collected by the app.

After the BuzzFeed report, nine Republican senators — including Marsha Blackburn of Tennessee and John Thune of South Dakota — wrote to TikTok with questions about its security practices. Last month, a member of the Federal Communications Commission also said Apple and Google should remove TikTok from their app stores. And last week, TikTok sent U.S. lawmakers a letter detailing how it planned to keep data about its American users separate from its Chinese parent company.