President Donald Trump has announced he is banning the Chinese-owned video-sharing app TikTok in the US.

He told reporters he could sign an executive order as early as Saturday. US security officials have expressed concern that the app, owned by Chinese firm ByteDance, could be used to collect the personal data of Americans.

TikTok has denied accusations that it is controlled by or shares data with the Chinese government.

The fast-growing app has up to 80 million active monthly users in America and the ban would be a major blow for ByteDance.