Verstappen not for sale - Marko

Apr.16 (GMM) Max Verstappen is not for sale, Red Bull driver manager Dr Helmut Marko insisted on Thursday.

The hype around the 17-year-old sensation is now swirling, particularly after his spectacular drive in China that ended with Renault engine failure.

Unfortunately, Renault cannot rule out more of the same problems at Toro Rosso and Red Bull in Bahrain, given the nature of 'flyaway back-to-back' race weekends.

"Due to logistics of the back-to-back races a complete guarantee will be difficult but we have made improvements to prevent the race stoppers we saw in China," said Cyril Abiteboul.

Marko, in charge of Red Bull's driver programme, said he was impressed with how Dutchman Verstappen dealt with the setback in China, as he was on course for another points finish.

"Max is doing a great job," said the Austrian.

Rumours are now firing that Verstappen, despite his young age, is on the fast track to a top team.

"We'll see. He should develop for now in peace," Marko told f1-insider.com.

But if Toro Rosso is bought by Renault, Verstappen might already be a works driver for the French marque in 2016.

"Toro Rosso is not sold. If anything, there will be a sponsorship," Marko insisted.

But what if a big team like Mercedes makes an offer for Verstappen? The German marque's boss Toto Wolff on Thursday had to admit a new contract with Lewis Hamilton beyond 2015 still has not been signed.

The Austrian even had to deny Hamilton is demanding 'number 1' status.

"That is not the case," Wolff told Britain's Sky, "and he wouldn't ask for that because it's not what we do and I think he appreciates how we manage the team, giving both drivers equal status."

But if Mercedes did come knocking for Verstappen, could Toro Rosso afford to turn it down?

Marko, however, insists Verstappen "has a long-term contract with Red Bull, not Toro Rosso. And he is not for sale."