The popular video-sharing app TikTok is facing accusations of violations of privacy, data fraud and unfair competition.

According to a class-action lawsuit filed in California federal court last week, TikTok is secretly sending users’ personal data to servers in China.

The lawyers of the university student who filed the lawsuit, claim that, after she downloaded the app, TikTok created an account for her, without her knowledge, and produced a dossier of private information about her, gathered from videos she created but never posted.

The TikTok app is owned by Beijing ByteDance Technology Co, and operates entirely outside of China. It says that it stores all US user data in the United States, with backups in Singapore.

The app is particularly enjoyed among US teenagers.

The lawsuit also claims that the app has embedded source codes from Chinese advertising services, that were enabling developers to install spyware on a user’s phone.

TikTok became the first global social-media app that emerges from China, with 750 million downloads in the past year. The company not immediately respond to the allegations.