Red Bull advisor Helmut Marko has claimed Sebastian Vettel tried to evaluate the possibility of returning in 2021.

The Ferrari driver is out of contract at the end of this season and his future is under scrutiny after the impression made by Charles Leclerc last year.

Recently, Vettel was spotted with the Red Bull and AlphaTauri drivers at the Austrian ski resort of Kitzbuhel, and it was there, Marko claims he made his approach.

“Sebastian wanted to get a feeling whether there could be a return to us in 2021, but none of us who can make the decisions were there in Kitzbuhel,” told Germany's AutoBild.

Recently, Marko had already ruled out taking back Vettel after Max Verstappen re-signed until 2023 but explained it's not through a lack of talent.

“Sebastian is a four-time world champion and has certain financial claims, but since we have a new long-term contract with Max Verstappen, which wasn’t exactly cheap, we can’t afford a second heavyweight driver," he continued.

“That is unfortunately the case. Seb would have to come with very little money but you can’t ask him to do that.”

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With an obvious option off the table then for 2021, the Red Bull advisor does feel Vettel is in a tough spot if he wants to stay in F1.

“Sebastian is a bit of a transfer trap,” Marko added.

“Ferrari committed to Leclerc, we have committed to Verstappen. He can only do really well this season, which I trust him to do if he has a car that suits his driving style.

“If he clearly beats Leclerc, Ferrari has to think about him and then he would also be interesting for Mercedes.”

Away from Vettel, Marko has also ruled out hiring another former world champion who has been linked to Red Bull several times during his career.

“As things stand today, Fernando Alonso’s return with Red Bull is absolutely impossible to imagine,” he said, speaking with Motorsport-Magazin.

“There are two reasons for that. First, there is the relationship between Alonso and Honda, which I think is quite broken.

“And second, our entire Formula 1 structure is based on our junior program, which means that our young talents move to the top category of racing.

“If we signed Alonso, he would be the oldest driver on the grid and that would contradict our entire philosophy.

“But as we use a Honda engine, it is impossible anyway," he concluded.

Indeed, the Japanese manufacturer recently blocked the Spaniard from completing a deal with Andretti Autosport to compete in this year's Indy 500, highlighting the friction that remains.