President Donald Trump has unveiled sweeping bans on US transactions with China's ByteDance, owner of video-sharing app TikTok, and Tencent, operator of messenger app WeChat, in a major escalation of tensions with Beijing.

The executive orders, which go into effect in 45 days, come after the Trump administration said this week it was stepping up efforts to purge "untrusted" Chinese apps from US digital networks and called TikTok and WeChat "significant threats."

The hugely popular Tiktok has come under fire in the US over national security concerns surrounding data collection, amid growing distrust between Washington and Beijing.

On Wednesday, US Secretary of State Mike Pompeo expanded efforts on a programme dubbed "Clean Network" to prevent various Chinese apps as well as Chinese telecoms firms from accessing sensitive information on US citizens and businesses.

TikTok has 100 million users in the United States. TikTok's kaleidoscopic feeds of short video clips feature everything from hair-dye tutorials to dance routines and jokes about daily life. 

The company has announced plans for its first data center for European users, to be set up in Ireland. 

While WeChat is not popular in the country, the app, which has over one billion users, is ubiquitous in China. It is also widely used by expat Chinese as a main platform for communications with family and friends as well as a medium for various other services, such as games and e-commerce.

Operator Tencent is China's second most-valuable company after Alibaba at $686bn. It is also China's biggest video game company and earlier this summer opened a California-based studio.

President Trump issued the orders under the International Emergency Economic Powers Act, a law that grants the administration sweeping power to bar US firms or citizens from trading or conducting financial transactions with sanctioned parties.

US Commerce Secretary Wilbur Ross will identify transactions covered by the prohibition after the orders take effect in mid-September.

The development comes soon after the US ordered China to vacate its consulate in Houston, Texas, followed by China's order requiring the United States to vacate its consulate in the southwestern city of Chengdu.

But tension has been simmering between the two powers for months, with the United States taking issue with China's handling of the novel coronavirus outbreak and moves to curb freedoms in Hong Kong.

Mr Trump said this week he would support the sale of TikTok's US operations to Microsoft if the US government got a "substantial portion" of the sale price.

He nevertheless said he will ban the service in the US on 15 September, though some Republicans have raised concerns about the political fallout of banning the popular app.

The app may be used for disinformation campaigns that benefit the Chinese Communist Party, and the United States "must take aggressive action against the owners of TikTok to protect our national security," Mr Trump said in one order.

In the other, Mr Trump said WeChat "automatically captures vast swaths of information from its users. This data collection threatens to allow the Chinese Communist Party access to Americans' personal and proprietary information."

The order would effectively ban WeChat in the US in 45 days by barring "to the extent permitted under applicable law, any transaction that is related to WeChat by any person, or with respect to any property, subject to the jurisdiction of the United States, with Tencent Holdings Ltd."

Late yesterday some China watchers in Washington were already questioning the logic behind the orders.

The order "calls TikTok a national security threat," said Derek Scissors, an expert on Sino-US economic relations at the American Enterprise Institute think tank.

"Either we've missed the threat for three years or it just became one and yet we are waiting 45 days."