TikTok owner ByteDance stole content from Snapchat and Instagram to boost TikTok engagement, according to a former employee who is suing the company for wrongful termination.

As The New York Times reports, Yintao Yu, who was head of engineering for ByteDance’s US operations between August 2017 and November 2018, claims he was fired because he raised concerns about ByteDance stealing and profiting from other companies’ intellectual property to increase TikTok engagement and user numbers.

Yu also alleges that at the time of his employment, ByteDance’s Beijing offices had a special unit of Chinese Communist Party members nicknamed the Committee, which tracked ByteDance apps including TikTok. This Committee is also alleged to have “guided how the company advanced core Communist values," the Times notes, and had access to all company data including US stored data.

Yu also says ByteDance used bots to inflate TikTok’s app engagement metrics when it was launched as Musical.ly. According to the Times, Yu says he raised concerns with a senior staffer in charge of the TikTok algorithm but was rebuffed and told that his worries were “not a big deal.”

In an emailed statement reported by the Times, ByteDance called the allegations “baseless.” The statement continued: “Mr Yu worked for ByteDance Inc. for less than a year and his employment ended in July 2018. During his brief time at the company, he worked on an app called Flipagram, which was discontinued years ago for business reasons.”

TikTok has come under extensive scrutiny from US legislators in recent months because of claims that ByteDance puts US users' personal data at risk. Lawmakers at both the federal and state level have argued that American data could be shared with the Chinese government. TikTok CEO Shou Zi Chew was grilled in March by a congressional committee on those widely held concerns.

The short-form video app has repeatedly denied these accusations, and in a move to gain standing among US legislators, TikTok injected more than $1 billion into creating a means for American user data to be exclusively stored on servers run by US tech company Oracle.

Last week, it emerged that TikTok compiled a list of users who watch LGBT content on the app. TikTok users who watched LGBT content were included on a list that could be viewed by authorized staff. Users were identifiable from their ID number, which TikTok gives each user when they start watching videos on the popular app.