Raikkonen is believed to be among the top-three earners in Formula One alongside Ferrari's Fernando Alonso and Mercedes' Lewis Hamilton, even outstripping triple world champion and potential future new team-mate Sebastian Vettel

The 33-year-old and Toro Rosso's Daniel Ricciardo are now the only two names in the frame for the seat to be vacated by Mark Webber at the end of the season.

Ricciardo's Toro Rosso team-mate Jean-Eric Vergne was initially in the running, but Horner has now claimed it is "too early" in the Frenchman's development for him to be considered.

While money is hardly an issue for a team as wealthy as Red Bull, who are backed by billionaire Dietrich Mateschitz, the founder of the energy drinks company, Horner maintains finances play a role.

But as far as possibly recruiting Raikkonen is concerned, Horner said: "It is not really an element in our decision-making.

"Of course, finances are always a factor. But you can contrast it with the difference between first and second, or second and third or fourth in the constructors' championship, which is a significant amount.

"So the financial element, if you don't make the right decision, is going to impact on you anyway if you are not scoring points."

It is where Raikkonen's experience and renowned pace appear to give him the edge over Ricciardo.

Horner has reaffirmed a decision will be taken over the forthcoming summer break, after this weekend's Hungarian Grand Prix, and relayed either in Belgium or Italy.

Raikkonen, however, has again suggested he has already received an offer, indicating he has a choice between Red Bull and current team Lotus, who are desperate to retain his services.

Raikkonen said: "It's about whatever feels right for me, both with regard to the racing and away from racing. Basically everything just has to feel right.

"Whatever the decision will be it might feel stupid to somebody else, but then it might feel right for me.

"I have no idea what will happen. We will have to wait and see, but hopefully whatever it will be, it will be the right choice."

Horner, however, insists Ricciardo has the speed, particularly after impressing during last week's young driver test at Silverstone when he was given half a day in a Red Bull.

"Daniel is certainly a very quick racing driver," added Horner.

"Part of the challenge of being a driver at Red Bull is that it's not just about being quick - it's about having the ability with regard to feedback to fully converse with the engineers.

"For any driver to go up against Sebastian, there is inevitably a pressure that will come from being measured against him and you have to be fairly broad-shouldered to deal with that.

"So there is an expectation that perhaps isn't there in Daniel's current team. The scrutiny from you guys (the media) isn't there.

"The pressure on any driver in a front-running team is always that bit greater, but what Daniel has demonstrated so far has been very positive."