US President Donald Trump has said that he and his Chinese counterpart Xi Jinping approved a deal on the future of TikTok's US operations during a phone call on Friday, although there was no confirmation from Beijing.

Trump wrote on Truth Social that the call was productive and he appreciated Xi's approval of a deal, which would reportedly see TikTok’s US business sold to a group of US investors.

China's official state news agency Xinhua left the outcome of their discussion less clear, with Xi quoted as saying that Beijing welcomes negotiations over TikTok.

TikTok, which is run by Chinese firm ByteDance, was previously told it had to sell its US operations or risk being shut down.

Trump, however, delayed implementing the ban four times since it was first announced in January, and earlier this week extended the deadline again to December.

In his post, Trump wrote the two had made progress on trade issues and would meet at the Asia-Pacific Economic Cooperation (Apec) summit, scheduled to begin at the end of October in South Korea, and said he would travel to China.

I also agreed with President Xi that we would meet at the Apec Summit in South Korea, that I would go to China in the early part of next year, Trump said, adding that Xi would travel to the US at an appropriate time.

Trump told reporters on Friday afternoon that a deal still had to be signed, and signalled there could be a formal process to do so soon.

We look forward to getting that deal closed, he said, adding that the US would have very tight control of the app.

That deal will reportedly see a group of US firms, said to include Oracle, which was co-founded by Trump ally Larry Ellison, that would enable TikTok to continue operating in the US, using algorithm technology licensed from ByteDance.

A sticking point in negotiations appears to be who will own the powerful algorithm that pushes content to TikTok's 170 million American users.

Trump added he believes TikTok has tremendous value to the US. The people that are investing it are among the greatest investors in the world, he said.

Xinhua reported that China's position on TikTok is very clear and that it welcomed firms to conduct commercial negotiations based on market rules and reach solutions that comply with Chinese laws and regulations.

Many US lawmakers have expressed unease with the prospect of a deal, citing ongoing concerns about ByteDance's links with the Chinese Communist Party. While Trump initially called for TikTok to be banned during his first term, he has changed course.

The call between Xi and Trump is the second so far this year, with previous discussions focusing on trade and other economic issues.