Rival technology giant Huawei has also cut smartphone prices in the run-up to the Lunar New Year holiday.

It is the time of year when new handsets are unveiled, but they may offer only small improvements.

The technology giant's stock market valuation has fallen by almost $200bn in the last two days.

It is the latest move by the US government to stop sales of sophisticated technology to China.

An increasing number of countries are putting curbs on TikTok and other Chinese technology firms.

Five years since the trade war started, American firms seem less inclined to invest in China.

Washington has been tightening its rules on exports of US technology to China for several years.

The restrictions on five Chinese companies are the first to be put in place on security grounds.