Earlier, amid rumours he has been offered a Renault seat for 2018, the young Spaniard said it was indeed “unlikely” he will stay at Toro Rosso next year.
Horner, the Red Bull boss, called Sainz “disingenuous”, while Red Bull driver manager Marko was even harsher in his reaction to his comments.
“He must be confused,” Auto Motor und Sport quotes the gruff Austrian as saying.
“He knows his contract situation so if he putting pressure on us, it’s the wrong way. He signed a contract with us in 2018. No ifs and buts.
“I have to wonder about his behaviour,” Marko added. “Normally you do not bite the hand that feeds you.
“I think he should concentrate more on his racing. In the last races, Kvyat was always in front.
“Maybe it is his father (Carlos Sainz snr) who is dreaming,” he said.
Even Franz Tost, Sainz’s normally fully supportive Toro Rosso chief, hit back at the 22-year-old, insisting: “Red Bull paid and financed his whole career.
“Why should Red Bull give him away to another opponent?”
When asked if he was surprised by the ‘hype’ that followed his original comments in Austria, Sainz replied: “I would not call it hype, that’s too strong a word.
“But in my opinion, from what I said yesterday it’s a bit exaggerated because I think I said nothing strange.
“I have serious sporting ambitions and I have always said my main goal is to become a driver for Red Bull Racing. I owe everything to this company,” he explained.
As for whether Horner, Marko and Tost’s reaction ‘surprised’ him, Sainz continued: “I can say that I was a little surprised, but such things can often happen in formula one.
“It’s no problem, I can talk to them — about Red Bull, my devotion to the company, about what I want to achieve. What can I say? I think my words were misinterpreted.
“What I said is a fact, because no one has driven for Toro Rosso for more than three years. It’s a youth team, where drivers gain experience, so in my opinion with what they say about me, it’s a little strange.
“I just called a spade a spade while expressing loyalty to Red Bull,” he insisted.