The Navy said users of government issued mobile devices who had TikTok and did not remove the app would be blocked from the Navy Marine Corps Intranet.

Pentagon spokesman Lieutenant Colonel Uriah Orland said in a statement the order was part of an effort to "address existing and emerging threats".

The US government has opened a national security review of the app's owner Beijing ByteDance Technology Co's $1 billion acquisition of US social media app Musical.ly, Reuters first reported last month.

Earlier this week, the United States Navy banned the social media app TikTok from government-issued mobile devices, saying the popular short video app represented a "cybersecurity threat."

A bulletin issued by the Navy on Tuesday showed up on a Facebook page serving military members, saying users of government issued mobile devices who had TikTok and did not remove the app would be blocked from the Navy Marine Corps Intranet.

The Navy would not describe in detail what dangers the app presents, but Pentagon spokesman Lieutenant Colonel Uriah Orland said in a statement the order was part of an effort to "address existing and emerging threats".

TikTok did not return a request for comment.

TikTok is hugely popular with US teenagers, but has come under scrutiny from US regulators and lawmakers in recent months. The US government has opened a national security review of the app's owner Beijing ByteDance Technology Co's $1 billion acquisition of US social media app Musical.ly, Reuters first reported last month.

Last month, US army cadets were instructed not to use TikTok, after Senator Chuck Schumer raised security concerns about the army using TikTok in their recruiting.

A Navy spokesman said Naval and Marine personnel who use government issued smart devices are generally allowed to use popular commercial apps, including common social media apps, but from time to time specific programs that present security threats are banned. He would not give examples of apps that are allowed or those considered unsafe.

The Pentagon's Orland said the "Cyber Awareness Message" sent December 16 "identifies the potential risk associated with using the TikTok app and directs appropriate action for employees to take in order to safeguard their personal information."