They hit out after US President Joe Biden signed into law a bill that gives TikTok’s Chinese owner ByteDance nine months to sell its stake in the app or it will be blocked in America – a move TikTok says it will challenge in court.

Isobel Perl, founder of Perl Cosmetics in London, is among the army of web traders worried about the impact of a ban as a quarter of her sales now come from the US.

She told the BBC: “(A US ban) could be potentially devastating to businesses in the UK – TikTok is quite a unique way of reaching customers.

“I mostly use TikTok to drive sales to our website. Of all the social media apps it drives the most traffic.”

Around 1.5 million UK businesses operate on TikTok.

Kyle Frank, founder of Franks Remedies, is another worried about the impact of a US ban on the app as he sells huge amounts of his skincare products in the country through the app.

He added to the BBC: “Certain months 60 to 70 per cent of our monthly sales have come from the US.”

America is now Kyle’s second biggest market, with TikTok vital in breaking it.

He said: “We haven’t really had to spend any money on ads or marketing to get those customers and connect with them.”

US officials have raised alarm over TikTok’s popularity with young people and Biden’s law has been introduced amid worries the company may share user data with the Chinese government – claims it has always denied.

TikTok has said it would challenge the “unconstitutional” move in court.

It said in a statement: “The fact is, we have invested billions of dollars to keep U.S. data safe and our platform free from outside influence and manipulation.”

A spokesman for TikTok added the bill would “trample the free speech rights of 170 million Americans, devastate seven million businesses, and shutter a platform that contributes $24 billion to the US economy annually”.