The US Department of Justice (DoJ) has alleged in a legal filing that social media platform TikTok has been storing US customer data in China.

The allegations were made in documents filed on July 26, in which the department asked an appeals court judge to throw out legal challenges made by TikTok parent company ByteDance regarding a forced sale or ban of the service.

According to the FT, the DoJ has alleged that in order to address operational issues, TikTok employees shared sensitive US user data on an internal communication platform called Lark, which ByteDance has developed. The DoJ claimed that, as a result, this data has been stored on Chinese servers and is therefore accessible to ByteDance staff based in the country.

The department also alleged that ByteDance and TikTok employees both in the US and China have been able to collect user information and censor content based on certain words or topics, including religion, abortion, and gun control.

Casey Blackburn, assistant director of national intelligence at the Office of the Director of National Intelligence, said that “ByteDance and TikTok Global have taken action in response to [Chinese government] demands to censor content outside of China.”

TikTok has denied the allegation, saying in a statement to the FT that the US government “has never put forth proof of its claims, including when Congress passed this unconstitutional law.”

In its legal appeal, ByteDance has argued that the law violates the free speech rights of US citizens under the First Amendment. The DoJ has said that China, ByteDance, and TikTok Global are not covered by First Amendment rights and that users of TikTok do not have a constitutional right to access the platform.

In April 2024, President Joe Biden passed a law to force the sale of TikTok’s regional operations or face a ban. The bill gave ByteDance nine months to comply, with the possibility of a three-month extension to finalize a deal.

Former President Trump had previously tried to block the app but that effort failed when he lost his bid for reelection in 2020. However, he appears to have reversed that view, saying he would no longer ban the app if elected this year.

Since that failed attempt, ByteDance began moving its US TikTok workloads to Oracle Cloud in a $1.5 billion bid to show that it was willing to keep data local. In June, Oracle warned that a TikTok ban could impact revenue.

Last month, it was reported that ByteDance was working with Broadcom to develop an advanced AI processor. The two companies have worked together since 2022, with ByteDance having previously purchased Tomahawk 5nm high-performance switch chips and a Bailly switch for AI computer clusters from the US chip designer.