Facebook COO Sheryl told NBC's Dylan Byers she worries about the threat posed to the company by TikTok.

"They're huge, they're growing really quickly, they've gotten to bigger numbers faster than we ever did," she said.

Sandberg also said people have reason to worry about their privacy on the app because TikTok is a Chinese company.

Visit Business Insider's homepage for more stories.

Facebook's COO said she worries about the threat posed by TikTok, the short-form video app beloved by teens.

During an interview for NBC reporter Dylan Byers' podcast "Byers Market," Sandberg talked about the way social media companies compete for engagement. "In the world of tech we compete for every minute of your attention. Every day you pick up your phone, I mean my kids pick up the phone and they're on TikTok," she said.

Byers asked Sandberg if she worries about TikTok. "Sure [...] they're huge, they're growing really quickly, they've gotten to bigger numbers faster than we ever did," she said.

TikTok hit 1.5 billion downloads in November last year and was the third most-downloaded non-gaming app of 2019, outperforming both Facebook and Instagram.

"Of course we worry about it, we have to be worried about all the innovation," Sandberg added later.

TikTok's format has been seen by some as an antidote to apps like Instagram, which encourage users to craft the perfect picture over authenticity. Snap CEO Evan Spiegel said in January he thinks TikTok could overtake Instagram because it relies on "talent" rather than social posturing.

Sandberg also brought up concerns over TikTok's Chinese roots.

The app's parent firm is Chinese giant ByteDance. "They're a Chinese company, if people are concerned about data I think there's a lot to be concerned about there," she said.

US lawmakers have voiced misgivings about TikTok, asking whether the company might feed data back to the Chinese government. Multiple US government agencies including the army and navy have banned staff from using the app as a result.

TikTok has shot back against the accusations, stating it stores US user data in the US.

Sandberg isn't the first Silicon Valley exec to cite privacy concerns about TikTok. Reddit CEO Steve Huffman said during a panel on Wednesday that he views the TikTok app as "spyware."

Business Insider has approached TikTok for comment.