Alonso has given the clearest indication yet that he may not be at McLaren next year, commenting at the Spanish Grand Prix Thursday press conference that he will consider a future elsewhere if he does not feel McLaren can give him a competitive car for 2018.

The double world champion, who will make a one-off appearance in this year’s Indianapolis 500, has not ruled out leaving Formula 1 altogether.

"I like this F1. My intention or first priority is to race here," Alonso ahead of the Spanish Grand Prix. "I am happy with the team but we are not winning.

"If from here to September/October we are in a position where we see clearly a possibility to win in 2018, I will be more than happy to stay with the team.

"If it is not the case then I will be more than happy to talk to anyone.

"I will have to think a little bit after the summer as now it's not an easy period and with the Indy 500 thing will be difficult to think about something else."

Alonso left Ferrari at the end of 2014 hoping that McLaren-Honda would give him a better chance of winning the World Drivers’ Championship for a third time. But in what is currently his third season with McLaren, Alonso has failed to score a single podium position. At the same time the driver who replaced him at Ferrari, Sebastian Vettel, currently leads the 2017 World Championship.

Alonso’s contract with McLaren expires at the end of this year.