WASHINGTON -- US President Donald Trump on Thursday issued an executive order banning any U.S. 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 one 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 U.S. "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 U.S. 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 U.S. side's blatant bullying of certain non-U.S. 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.