TikTok's chief executive is facing tough questions from US representatives who are convinced the Chinese-owned short video app should be banned for being a "tool" of the Chinese Communist Party and because it carries content that can harm children's mental health.

CEO Shou Zi Chew's testimony before Congress capped a week of actions by the Chinese company aimed at convincing Americans and their politicians that the app creates economic value and supports free speech amid growing calls to ban the app.

TikTok, which has more than 150 million American users, was repeatedly hammered in the ongoing hearing where no representatives offered any support.

Many talked of a need to rein in the power held by the app over US children.

"TikTok could be designed to minimise the harm to kids but a decision was made to aggressively addict kids in the name of profits," said Representative Kathy Castor, a Democrat, at the House of Representatives Energy and Commerce committee hearing.

Republicans and Democrats also raised numerous concerns about its potential to threaten US national security by sharing its data with the Chinese government.

TikTok has said it has spent more than $1.5 billion on what it calls rigorous data security efforts under the name "Project Texas" that currently has nearly 1,500 full-time employees and is contracted with Oracle Corp to store TikTok's US user data. It also says it rigorously screens content that could harm children.

Representatives rejected TikTok's responses as insufficient.

'Poster child' for tensions

Representative Diana DeGette focused questions on TikTok efforts to prevent the spread of misinformation on the platform.

"You have current controls, but the current controls are not working to keep this information mainly from young people, but from Americans in general," Ms DeGette said.

Mr Chew said the company was investing in content moderation and artificial intelligence to limit such content.

A TikTok advertisement at Union Station in Washington, DC

Ms DeGette said TikTok's actions were not enough.

"You gave me only generalized statements that you're investing, that you're concerned, that you're doing work. That's not enough for me. That's not enough for the parents of America," Ms DeGette said.

Shares of US social media companies rose today, with Facebook parent Meta Platforms up 3.4% and Snap Inc up 4.4%.

Wedbush analyst Dan Ives said on Twitter the "TikTok CEO testimony so far we would characterise as a 'mini disaster' for this key moment for TikTok. TikTok is now poster child of the US/China tensions and lawmakers have a lot of q’s with not enough concrete answers."

'Every data point imaginable’

Committee chair Cathy McMorris Rodgers, a Republican, set the tone of the hearing by saying: "TikTok collects nearly every data point imaginable - from people's location to what they type and copy, who they talk to, to biometric data and more.

"We do not trust TikTok will ever embrace American values - values for freedom, human rights and innovation," she said, adding that the Chinese Communist Party "is able to use (TikTok) as a tool to manipulate America as a whole".

Mr Chew, who began his testimony speaking about his own Singaporean roots, said, "We do not promote or remove content at the request of the Chinese government."

He added: "It is our commitment to this committee and all our users that we will keep (TikTok) free from any manipulation by any government."

Shou Zi Chew arrives at the US capitol to testify before Congress

But the top Democrat on the panel, Representative Frank Pallone, argued with that statement, saying, "You're going to continue to gather data, you're going to continue to sell data ... and continue to be under the aegis of the Communist Party".

Many US lawmakers want TikTok banned.

TikTok last week said President Joe Biden's administration demanded its Chinese owners divest their stakes or face a potential ban.

China’s Ministry of Commerce at a briefing today said that "forcing the sale of TikTok will seriously damage the confidence of investors from all over the world, including China, to invest in the United States. If the news is true, China will firmly oppose it."

"The sale or divestiture of TikTok involves technology export, and administrative licensing procedures must be performed in accordance with Chinese laws and regulations, and the Chinese government will make a decision in accordance with the law," the ministry representative added.

Democratic Senator Mark Warner yesterday said two additional senators backed his bipartisan legislation with Republican John Thune to give the Biden administration new powers to ban TikTok - raising the total to 10 Democrats and 10 Republicans.

Representatives from TikTok are due to appear before the Oireachtas Committee on Media in the coming weeks.