Fernando Alonso has 10 years to win Le Mans 24 Hours

Webber returned to sportscar racing with Porsche after his F1 career ended at the age of 37 and won the 2015 World Endurance Championship title before retiring at the end of last season.

He believes good friend Alonso, 35, has time on his side when it comes to the Le Mans element of his bid to become only the second driver to win the 24 Hours along with the Indy 500 and Monaco Grand Prix.

"He can do it in the next 10 years; there's no rush," said Webber.

"The Indy 500 in his eyes is the harder one to get, and I would probably agree with him.

"He can take time to get Indy and then the opportunity has to be there to win Le Mans, which can also take a while."

Porsche and Toyota, the two manufacturers involved in the LMP1 division in the WEC, have both dismissed the chance of Alonso joining them for Le Mans next year.

Webber has no doubts that Alonso, who is racing a Honda-powered Dallara for the Andretti team at this year's Indy 500 on May 28, has the potential to become only the second driver after Graham Hill to complete the triple crown.

"His skill is not in question; I believe, yes, he can win both races - he has the hunger and the mindset," Webber continued.

"Hats off to him for giving it a go."

Webber revealed that Alonso had joked with him about also racing at Indy this year.

But he said that he had never had any interest in competing in the Indy 500 during his career.

He did divulge that he had been in talks with the Forsythe Racing CART team at the end of 1999 to take the place of Greg Moore, who was due to swap to Penske before his death at Fontana that year.

The team ultimately signed Alex Tagliani as Patrick Carpentier's 2000 team-mate and Moore's death then dissuaded Webber from pursuing CART options further.

"There was a chance I could go to 'Indycar' racing with Forsythe, because Greg Moore was going to Penske," he explained.

"Tragically he lost his life at Fontana and after that I decided to stay in Europe."