House Republicans are accusing TikTok of providing congressional staff with “false or misleading” information about the app’s use of user data during a September briefing.

“We still have unanswered questions and you failed to provide responsive documents requested by the Committee. Additionally, some of the information TikTok provided during the staff briefing appears to be untrue or misleading, including that TikTok does not track U.S. user locations,” the lawmakers wrote in a letter dated Tuesday to TikTok CEO Shou Zi Chew. 

Reps. James Comer (R-Ky.) and Cathy McMorris Rodgers (R-Wash.) — the ranking members of the Committee on Oversight and Reform and the Committee on Energy and Commerce, respectively — said in the letter that TikTok assured lawmakers it did not track users’ internet data while they weren’t using the app and that China-based employees can’t access U.S. user data.

“Both claims appear to be misleading at best, and at worst, false,” the lawmakers wrote. 

Comer and Rodgers are asking the TikTok CEO to turn over a number of documents, electronic records and communication related to their concerns, with a deadline of Dec. 6.

They’re also asking for “all drafts and iterations” of any agreement with the Biden administration that would allow TikTok to continue operating within the U.S.

Republican lawmakers have long been looking at TikTok, which is owned by China-based parent company ByteDance, but the new letter may signal the party is ramping up probes as it prepares to take control of the House in the next Congress. 

GOP lawmakers have said they plan to probe a number of topics, including the U.S.-Mexico border, the U.S. withdrawal from Afghanistan and the origins of the COVID-19 pandemic. 

House Minority Leader Kevin McCarthy (R-Calif.) said earlier this week he plans to kickstart a House select committee on China if he’s elected Speaker of the new, GOP-majority house, to press China on the COVID-19 pandemic. 

But concern over TikTok hasn’t been confined to the GOP, and many have raised concerns about its ties to the Chinese government and its usage of U.S. user data. 

Democratic Sen. Mark Warner (Va.), chairman of the Senate Intelligence Committee, earlier this week called TikTok an “enormous threat” and said parents should be “very concerned” about their children’s use of the app.

“All of that data that your child is inputting and receiving is being stored somewhere in Beijing,” Warner said.