TikTok CEO Shou Zi Chew faced relentless questioning from US lawmakers on both sides of the political aisle on Thursday over the video-sharing app's alleged ties to the Chinese government.

The Harvard-educated former banker failed over several grueling hours to defuse an existential threat to TikTok as the app seeks to survive a White House ultimatum that it either split from its Chinese ownership or get banned in the United States.

In the morning session of the House Energy and Commerce Committee hearing, lawmakers frequently denied Chew opportunities to expand on his answers or tout the site's huge global popularity with young people.

"ByteDance is not owned or controlled by the Chinese government and is a private company," Chew told lawmakers in his opening remarks, referring to TikTok's China-based parent company.

"We believe what's needed are clear transparent rules that apply broadly to all tech companies -- ownership is not at the core of addressing these concerns," Chew added.

A ban would be an unprecedented act on a media company by the US government, cutting off 150 million monthly users in the country from an application that has become a cultural powerhouse -- especially for young people.

"TikTok has repeatedly chosen the path for more control, more surveillance and more manipulation. Your platform should be banned," committee chair Cathy McMorris Rodgers said as she began the hearing.

Ahead of the hearing, the commerce ministry in Beijing said it would "firmly oppose" a forced sale, underlining that any deal or spin-off of TikTok would require approval by Chinese authorities.

"Forcing the sale of TikTok... will seriously undermine the confidence of investors from various countries, including China, to invest in the US," said spokesperson Shu Jueting.

Chew's testimony promoted the company's plan -- known as Project Texas -- to satisfy national security concerns, under which the handling of US data will be ring-fenced into a US-run division.

But lawmakers said this would do nothing to remove their concerns that TikTok was vulnerable to China. (AFP)