The US Senate has approved a bill that could see TikTok banned in America over national security fears. Photo: Reuters

It gives TikTok's Chinese owner, ByteDance, nine months to sell its stake or the app will be blocked in the United States.

The bill will now be handed over to US President Joe Biden, who has said he will sign it into law as soon as it reaches his desk.

TikTok has told the BBC that it did not have an immediate response to the move. Previously, Bytedance said it would oppose any attempt to force it to sell TikTok.

"It's a big deal", Doug Calidas, a tech expert at Harvard University's Belfer Center, told the BBC.

"In the period of a few weeks they managed to pass a law through both chambers which very rarely happens - to see them act so quickly on a matter of public concern."

If the US is successful in forcing ByteDance to sell TikTok, any deal would still need approval from Chinese officials - but China has vowed to oppose any such move.

It could take several years before the app is blocked in the US, as legal action from ByteDance, likely all the way to the Supreme Court, would delay the process.

The legislation then allows the company nine months to sell TikTok, with an additional three-month grace period.

There is also the small matter of who would be able to buy and operate it - the price would likely be in the tens of billions - meaning there would be few potential buyers.

If it is not sold in time, the app could then be blocked in the country - the US says this is because it is concerned TikTok could be used to spy on Americans, or to spread propaganda.

TikTok gathers similar kinds of data to other apps, but the US is concerned this data could fall into the hands of the Chinese government - claims the company has always contested.

US politicians may also face a public backlash - it has more than 170 million users across the country.