Formula F1 driver Michael Andretti "has already taken over 80 percent" of the Swiss-based Formula 1 team currently known as Alfa Romeo.

That is the claim of veteran Swiss F1 journalist Roger Benoit, whose report in Blick newspaper mirrors widespread rumours in the Istanbul paddock.

Team boss Frederic Vasseur, who runs Sauber Motorsport at Hinwil and at the grands prix, is not yet ready to confirm the news.

"If all the reports I've read in the last few weeks were true, we'd have sold the team 25 times already," he said.

"I hope the current owners got some good business out of it. In the end, it's they who will decide."

Andretti, the son of F1 legend Mario, is now a major player in the chiefly US-based motor racing industry, with teams in Indycar, Formula E and elsewhere.

The transaction could explain why Alfa Romeo is now the only team in pitlane with an official race driver vacancy for 2022.

It had been rumoured that the well-financed Chinese driver Guanyu Zhou had secured the place, but Vasseur now insists that a driver agreeing to a "one-year deal" may be a wiser choice.

Top of the list now may be Formula 2 frontrunner and Australian Oscar Piastri - but the issue with that is his links with the Renault-Alpine program.

"When you are taking a young driver with a new car and starting a new journey, I think it would make much more sense to have the possibility to extend the contract," said Vasseur.

"Not a multi-year contract but at least to be sure that you won't lose the driver after year one."

Vasseur's personal favourite is Theo Pourchaire, but 2022 would be too soon for his 18-year-old fellow Frenchman.

So the latest name linked with the team is Andretti's top Indycar driver, 21-year-old Colin Herta.

When asked why the identity of Valtteri Bottas' 2022 teammate is so delayed, Vasseur said in Turkey: "Because we are discussing with all the parties involved and it's not an easy choice.

"We will take a decision in the next couple of weeks most probably."