Fernando Alonso has played down speculation that he could quit Formula 1 and switch full-time to the American equivalent Indycar.

The Spaniard is not in Monaco this weekend as he bids for Indy 500 victory, and motor racing legend Mario Andretti thinks that it is possible Alonso could make a permanent switch.

Alonso, on the other hand, says that it is possible he will not even return to do the Indy 500 in future.

"I do not have it in my plans," Spanish media quote him as saying.

"For now it's an isolated race that I wanted to do, and I have felt good, but repeating it is not in my plans.

"My first and exclusive objective is to continue and to win in F1. The 500 and Le Mans are very attractive, but not in the very short term. Little by little."

McLaren executive Zak Brown agrees, saying that Alonso's Indy 500 bid was a good opportunity for the British marque and for the Spaniard.

"We have good sponsors who deserved recognition, so it was a good response for the lack of exposure we have now in Formula 1," he is quoted as saying by AS.

Brown also said that the Indy 500 experience has been good for Alonso.

"I think he is smiling now, and as long as he sees that we (the F1 team) are going in the right direction, I think he will continue to be patient.

"But Fernando is clear that he has not yet finished in Formula 1. He will not rule out Indycar in the future but not in 2018. It's clear that he wants to be in F1."

Alonso has experienced a frustrating F1 season so far, with McLaren sitting bottom of the team rankings.