President Donald Trump has cast fresh doubt over the future of TikTok in the US unless Oracle and Walmart have "total control" of the company.
TikTok escaped a US ban on Sunday, after striking a deal with the American companies.
China-based owner Bytedance earlier said it would retain an 80% stake in the new company, TikTok Global.
But President Trump said: "They will have nothing to do with it.
And if they do, we just won't make the deal.
" 'Controlling interest' He had threatened to ban the app on security grounds unless a sale was agreed with a US company by the middle of September.
The two main US investors, Oracle and Walmart, have said they will be taking a combined 20% stake in TikTok Global.
But Mr Trump, naming the two companies, said: "They are going to have total control of it.
"They are going to own the controlling interest.
"And then I guess they are going public and they are buying out the rest of it, they are buying out a lot.
"If we find that they don't have total control, then we are not going to approve the deal.
" 'False rumours' Mr Trump had previously publicly given the proposed deal his blessing - but there have also been conflicting messages from the companies involved.
Oracle has confirmed its planned 20% bid with Walmart - but has also issued a statement from its executive vice-president, saying: "Americans will be the majority.
"And ByteDance will have no ownership in TikTok Global.
" Bytedance, meanwhile, wrote on its Chinese language website it wanted to offer an "explanation of some false rumours".
As well as saying it would keep an 80% stake in TikTok Global, it said there was no plan to transfer ownership of the valuable algorithms that power TikTok.
It also said it had not heard about a $5bn (£4bn) contribution to a new education fund, requested by President Trump at a rally in North Carolina.
Mr Trump said at the weekend that he had asked the companies involved to put up the money "so we can educate people as to the real history of our country".
TikTok said the $5bn figure was "a forecast of the corporate income tax and other operating taxes that TikTok will need to pay for its business development in the next few years" and said it had not been finalised.
It added, in a statement made on social media: "We would like to clarify that this is the first time that we have heard the news about a $5bn education fund".
"China has been determined to emphasise in recent months that the country still has full control of TikTok, amid nervousness at home over the company potentially being divested," said the BBC's China Media Analyst Kerry Allen.
"When Oracle agreed a deal with ByteDance last week so that TikTok could remain active in the States, Chinese media emphasised that the deal was "co-operative", with both parties playing an equal part, rather than Oracle bailing out the Chinese tech giant.
" But China may yet decide that it does not approve of the deal, said Dr Richard Windsor, founder of research firm Radio Free Mobile.
That's because while Bytedance may retain TikTok's algorithm, it will still run on US Oracle's infrastructure.
"If one flips the deal on its head and imagines a situation where a world-leading piece of US software was going to be run on Chinese servers where a Chinese company had full access to it, one can start to see why China might object," he said.