Donald Trump has said he will "most likely" give TikTok a 90-day reprieve from a ban that is due to take effect on Sunday, on the eve of his swearing-in as the 47th US president.

Trump told NBC News an announcement on the matter would probably come on Monday once he takes office.

It comes after the social media platform warned it would "go dark" on Sunday unless the outgoing Biden administration gave assurances the ban will not be enforced.

The Supreme Court on Friday upheld a law banning the app in the US unless its China-based parent company, ByteDance, sells the platform by 19 January. ByteDance has refused to seek a buyer.

"The 90-day extension is something that will be most likely done, because it's appropriate. You know, it's appropriate. We have to look at it carefully. It's a very big situation," Trump said in a phone interview with NBC News.

He made similarly remarks hours later to ABC News.

"Well, I have the right as you know, I'm the one who is going to be calling the shots," he told ABC. "Most likely, I'll extend for 90 days - you have the extension for 90 days as you probably know. I'll do that until we figure something out."

TikTok said late on Friday that the White House and the Department of Justice had "failed to provide the necessary clarity and assurance to the service providers that are integral to maintaining TikTok's availability".

But White House press secretary Karine Jean-Pierre said on Saturday that TikTok's warning it was about to go dark was "a stunt".

"We see no reason for TikTok or other companies to take actions in the next few days before the Trump administration takes office on Monday," she said.

"We have laid out our position clearly and straightforwardly: actions to implement this law will fall to the next administration. So, TikTok and other companies should take up any concerns with them."

Trump said on Friday he had spoken to China's President Xi Jinping and discussed TikTok, among other issues.

TikTok's CEO Shou Zi Chew is expected to be among tech executives at Trump's inauguration on Monday.

US national security officials have warned that Chinese spies could use the app's data to track American federal employees and contractors, which TikTok has denied.

On Friday, the Chinese embassy in Washington DC accused the US of unfairly suppressing TikTok: "China will take all necessary measures to resolutely safeguard its legitimate rights and interests," a spokesperson said.

The platform is wildly popular among the 170 million users it says it has in the US. It has also proved a valuable tool for American political campaigns to reach younger voters.

Trump previously backed a TikTok ban, but has more recently professed a "warm spot" for the app, touting the billions of views he says his videos attracted on the platform during last year's presidential campaign.

Under the law passed last April, the US version of the app would be removed from app stores and web-hosting services in the coming days.

Content creators and small businesses dependent on the app for revenue told the BBC their lives would be changed inordinately if it is shut down.

"Indirectly, TikTok was the majority of my income because all brands want their stuff to be promoted on the app," Nicole Bloomgarden, a fashion designer and artist who uses TikTok, told the BBC.

TikTok did not respond to a BBC inquiry about what it means by potentially "going dark" in the US.

One possible outcome is what happened in India when the platform fell foul of the authorities there.

Prime Minister Narendra Modi moved to switch off dozens of Chinese-owned apps, including TikTok, in 2020 after a deadly altercation with Chinese forces along contested borderlands.

Two weeks later, India's 200 million users of TikTok were no longer able to log in after internet providers there were directed to block access to the app.

App stores run by Google and Apple also stopped offering TikTok, which did not legally challenge India's ban.

Since the ban, short-form platforms from competitors have largely filled the void with TikTok copycats Meta-owned Instagram Reels and Google-owned YouTube Shorts.

Meta is widely viewed as the net winner from India's TikTok ban. (BBC)

Update news