Red Bull says having a winning car is key to retaining Sebastian Vettel long-term

Vettel has a contract with the team until 2014, having joined the Milton Keynes squad in 2009.

Since then he has won two titles and taken 20 wins to become the youngest double champion in history.

Marko believes Vettel's loyalty to Red Bull cannot be taken for granted, as he is aware that the German will always want to be in winning car.

He is confident, however, that Red Bull will be very strong in years to come.

"We do not prefer extra long-time security and employment guarantees," Marko told AUTOSPORT in a interview. "We will have a look when it is necessary.

"The basis for Vettel to stay with us is to present a winning car to him. We cannot offer a glorious past in racing. Sebastian will drive where he gets the best possible package that creates the highest possibility of winning.

"Having said that, I can assure you that we will be in a strong position. Who except Ferrari has an engine deal in place for 2014 and beyond?"

Marko also made it clear that, while the team believes stability is key to success, it will always try to hire the best people.

"People in all key positions are under contract until and through 2014. You know we rely on continuity, however we avoid running into a standstill. We will continuously optimise our staff."