US President Donald Trump has announced sweeping restrictions against Chinese-owned social media giants TikTok and WeChat, his latest explosive move aimed at countering China's rising global power.

Trump on Thursday signed executive orders giving Americans 45 days to stop doing business with the Chinese platforms, effectively setting a deadline for a potential pressured sale of viral video sensation TikTok to Microsoft.

The president cited national security concerns for the moves, which also threw into doubt the American operations of WeChat's parent firm, Tencent, an uber-powerful player in the video gaming industry and one of the world's richest companies.

Trump has taken an increasingly heavy hammer to US relations with China, challenging it on trade, military and economic fronts, and Thursday's effort provoked more outrage in Beijing.

The new restrictions sent Tencent shares into a spin, with the issue tanking as much as 10 per cent at one point in Hong Kong trade, wiping almost $50 billion off its market capitalisation.

Other Asian markets also took note, with investors concerned about increasingly bitter relations between the economic titans that some fear could lead to a renewal of their painful trade war.

Officials from both sides are due to meet next Saturday to review a trade deal signed earlier this year.

“TikTok automatically captures vast swaths of information from its users, including Internet and other network activity information such as location data and browsing and search histories,” Trump's order said.

Data could potentially be used by China to track the locations of federal employees and contractors, build dossiers on people for blackmail, and conduct corporate espionage, it alleged.

Beijing slammed the move as “arbitrary political manipulation and suppression” and said it would come at the expense of American users and companies.

Users of China's Twitter-like Weibo platform said the move would cut off many Chinese living and studying abroad.

“How can overseas students contact with their families once WeChat is banned?” one user wrote.

In a statement, TikTok vowed to “pursue all remedies available to us in order to ensure ... our company and our users are treated fairly — if not by the Administration, then by the US courts.” Tencent said in a statement it was “reviewing” the order.

Trump's move adds to a laundry list of issues that have ratcheted up tensions between the superpowers, including Hong Kong, trade, Huawei, Taiwan and the spread of the coronavirus.

'Watershed moment'

The TikTok mobile app has been downloaded about 175 million times in the US and more than a billion times around the world.

The US Senate voted Thursday to bar TikTok from being downloaded onto government employees' phones, intensifying scrutiny of the popular app.

The bill passed by the Republican-controlled Senate now goes to the House of Representatives, led by Democrats.

Several US agencies already bar employees from downloading TikTok onto their phones.

“This is yet another watershed moment in the US-China technology cold war,” Paul Triolo, head of global technology policy at Eurasia Group, told Bloomberg. “It shows the depth of the US concern.”

India last month also outlawed TikTok along with 58 other Chinese apps, citing data security fears.

Trump has set a deadline of mid-September for TikTok to be acquired by a US firm or be banned in the United States.

Microsoft has expanded its talks on TikTok to a potential deal that would include buying the global operations of the fast-growing app, the Financial Times reported on Thursday.

Microsoft declined to comment on the report, after previously disclosing it was considering a deal for TikTok operations in the US, Canada, Australia and New Zealand.

'Keeping tabs'

TikTok's kaleidoscopic feeds of short video clips feature everything from hair-dye tutorials to dance routines and jokes about daily life.

WeChat is a messaging, social media, and electronic payment platform and is reported to have more than a billion users. It is not widely used in the US, but in China it is difficult to function without it as the platform is used by nearly all businesses instead of email.

Trump's order contended that WeChat captures user data that could then be exploited by the Chinese government, but provided no evidence that is happening.

“WeChat captures the personal and proprietary information of Chinese nationals visiting the United States,” the order read, “thereby allowing the Chinese Communist Party a mechanism for keeping tabs on Chinese citizens who may be enjoying the benefits of a free society for the first time in their lives.”