WASHINGTON, March 15 (AFP) - The US government has told China-based ByteDance to sell its shares in the blockbuster TikTok app or face a national ban, the Wall Street Journal reported on Wednesday.

Western powers, including the European Union and the United States, have been taking an increasingly tough approach to the app, citing fears user data could be used or abused by Chinese officials.

Concern here ramped up earlier this year after a Chinese spy balloon was shot down in US airspace.

The White House last week welcomed a bill that would allow President Joe Biden to ban TikTok, US National Security Advisor Jake Sullivan said in a statement.

A bipartisan bill "would empower the United States government to prevent certain foreign governments from exploiting technology services... in a way that poses risks to Americans' sensitive data and our national security," Sullivan said.

The Senate bill and the backing of the White House accelerated the political momentum against TikTok, which is also the target of a separate piece of legislation in the US House of Representatives.

Appearing tough on China is one of the rare issues with potential for bipartisan support in both the Republican-run House and the Senate, where Biden's Democratic Party holds a majority.

TikTok claims it has more than a billion users worldwide including over 100 million in the US, where it has become a cultural force, especially for young people.

Activists argue a ban would be an attack on free speech, and stifle the export of American culture and values to TikTok users around the world.

US government workers in January were banned from installing TikTok on their devices.

Civil servants in the European Union, as well as in Canada are also barred from having TikTok on their phones.

According to the Journal report, the ultimatum to TikTok came from the US agency charged with assessing risks foreign investments represent to national security.

US officials as well as TikTok declined to comment on the report.

TikTok has consistently denied sharing data with Chinese officials, and says it has been working with the US for nearly two years to address national security concerns.

Time spent by users on TikTok has surpassed that spent on YouTube, Facebook, Instagram or Twitter and is closing in on streaming television titan Netflix, according to market tracker Insider Intelligence.