Red Bull team chief Christian Horner labelled Toro Rosso driver Carlos Sainz as 'disingenuous' on Friday for suggesting that he might switch teams next year.
Horner said Sainz was under contract to the Red Bull outfit, which controls Toro Rosso, and made it clear that the highly-rated Spanish driver was not likely to be freed.
Sainz, in his third season with Toro Rosso, said Thursday that he felt doubtful about doing another year in the same 'junior' team, but declined to suggest where he might go.
"We have an option on him for next year and the year after, so he'll be in a Toro Rosso again next year," said a bullish Horner in an effort to assert his authority.
Asked about the idea that Sainz may wish to move, he added: "I don't know where he thinks he'll be then! Contracts are clear.
"You have to remember that he only got an opportunity in F1 because of Red Bull investing in him in the junior years and it's a little disingenuous to be making comments like that when a lot of investment goes into these guys to give them the opportunity.
"Without Red Bull he wouldn't be sitting in an F1 car."
Sainz is the son of former world rally champion Carlos Sainz and was team-mate with Max Verstappen before the Dutch teenager switched to Red Bull last year.
Horner also played down reports that Renault were poised to sign Sainz on loan next year.
"I can't imagine that scenario," he said. "Toro Rosso are ahead of Renault at this point in time and doing a good job and it wouldn't make sense to loan him out."
Horner added that both Red Bull and Toro Rosso were planning to field unchanged drivers next year.