One of the commissioners of the U.S. Federal Communications Commission (FCC) has renewed calls asking for Apple and Google to boot the popular video-sharing platform TikTok from their app stores citing "its pattern of surreptitious data practices."

"It is clear that TikTok poses an unacceptable national security risk due to its extensive data harvesting being combined with Beijing's apparently unchecked access to that sensitive data," Brendan Carr, a Republican member of the FCC, wrote in a letter to Apple and Google's chief executives.

TikTok, in September 2021, disclosed that there are one billion people who use its app every month, making it one of the largest social media platforms after Facebook, YouTube, WhatsApp, Instagram, and WeChat.

Carr further emphasized that the short-form video service is far from just an app for sharing funny videos or memes, calling out its features as "sheep's clothing" intended to mask its core function as a "sophisticated surveillance tool" for amassing users' personal information.

The letter also references a litany of controversies that TikTok found itself in over the years, including skirting Android safeguards to track users online, accessing iOS clipboard information, and settling a class-action lawsuit for $92 million over allegations that it captured biometric and personal data from users in the U.S. without prior consent.

TikTok, which is owned by Beijing-based ByteDance and has denied ever sharing user data with the Chinese government, is back in the spotlight close on the heels of revelations from BuzzFeed News that U.S. users' data had been repeatedly accessed by employees based in China between September 2021 and January 2022 despite its assurances to the contrary.

"Everything is seen in China," a member of TikTok's Trust and Safety department was quoted as saying in a September 2021 meeting, while in another meeting held that month, a director referred to a Beijing-based engineer as a "Master Admin" who "has access to everything."

Last year, CNBC, citing former employees, similarly alleged that the social media app's Chinese parent company had access to TikTok's U.S. user data and that it's closely involved in the decision-making and product development.

In a statement shared with the business news publication, TikTok said engineers in locations outside of the U.S., including China, can be permitted access to U.S. user data on an "as-needed basis" under strict access controls.

TikTok has since announced that it's "changed the default storage location of U.S. user data" and that it's routing all information from its users in the country through infrastructure controlled by Oracle. However, Carr noted these efforts do not address the core concerns of data access.

"TikTok has long claimed that its U.S. user data has been stored on servers in the U.S. and yet those representations provided no protection against the data being accessed from Beijing." Carr said. "Indeed, TikTok's statement that '100% of U.S. user traffic is being routed to Oracle' says nothing about where that data can be accessed from."

It's worth noting that several U.S. military branches have already banned its members from using TikTok on government-issued devices due to possible security risks. In June 2020, the Indian government moved to block the app on similar grounds.