WASHINGTON -- US President Donald Trump on Thursday issued an executive order banning any US transactions with Chinese tech firm ByteDance, owner of popular video-sharing app TikTok, starting in 45 days, a controversial move widely criticized by experts.

The app has been downloaded over 175 million times in the United States and over 1 billion times globally, according to the executive order, which claims that the app automatically captures "vast swaths of information" from its users, posing risks to US "national security."

A similar executive order has also been issued for WeChat, a messaging and social media app owned by Chinese tech giant Tencent.

At a White House briefing earlier this week, Trump told reporters that he is open to a deal in which Microsoft Corp or another US company buy TikTok, setting Sept 15 as the deadline.

During a news briefing while commenting on the issue, Chinese Foreign Ministry Spokesman Wang Wenbin said Tuesday that China firmly opposes the US side's blatant bullying of certain non-US enterprises in violation of market economy rules and the World Trade Organization's principles of openness, transparency and non-discrimination.

"It is a blatant act of bullying, to which China firmly opposes. We have noticed that it has also drawn a flurry of criticisms and doubts in the United States and from the international community," Wang added.