Talks in Washington over the fate of the wildly popular Chinese short video app began weeks after Kevin Mayer, formerly a Disney executive, joined the company's ranks in June.

Kevin Mayer has quit his top post at TikTok, months after becoming chief executive of the Chinese video-sharing app accused by the Trump administration of jeopardising national security, according to a letter to employees seen by the Financial Times.

Mayer informed employees at TikTok and its parent company ByteDance of his decision to leave on Thursday, people briefed about the matter said. The former Disney executive's decision came shortly after President Donald Trump threatened a ban on TikTok in the US unless ByteDance sold its US assets to an American company by 15 September, "as the political environment has sharply changed", the top manager addressed his staffers.

"I understand that the role that I signed up for — including running TikTok globally — will look very different as a result of the US administration's action to push for a sell off of the US business", Mayer added.

One person familiar with his stint at Disney said when Mayer first joined the firm in June, weeks before the talks about the company's sellout kicked off:

"He has put himself in a sensitive political zone. He will have to align himself with both his Chinese masters and public scrutiny in the US".