The deal allows Alonso to continue his pursuit of motorsport's triple crown, which includes victories at the Indy 500, Le Mans 24 Hours and Monaco Grand Prix. Alonso currently has two Monaco victories to his name and last year competed in the Indy 500 for the first time but did not win.

Alonso will join former F1 drivers Sébastien Buemi and Kazuki Nakajima in the No.8 Toyota this season and his first race will be at the Six Hours of Spa-Francorchamps on May 5 before taking part in the 24 Hours of Le Mans on June 16-17.

"I've never been shy about my aim of winning motorsport's 'Triple Crown' - the Monaco Grand Prix, the Indy 500, and the 24 Hours of Le Mans. We tried for Indy last year, came close, but just missed out," Fernando Alonso said.

"This year, I have the chance thanks to McLaren to race for the win at Le Mans. It is a big challenge - much can go wrong - but I am ready, prepared and looking forward to the fight.

"My deal to race in WEC was only made possible through the good understanding and strong relationship I have with McLaren, and I'm very happy that they listened and understood what this means to me.

"In no way will this challenge take away from my main target of Formula 1 with McLaren. In 2018, my aim is to be competitive at every grand prix, and I feel sure that we are closer to achieving that."

Alonso's F1 team McLaren agreed to the deal on the proviso that his Formula One duties come first. Last year Alonso skipped the Monaco Grand Prix to compete at the Indianapolis 500 but he is set to compete all 21 rounds of the F1 world championship this year.

The only clash in 2018 comes on October 21 when the Six Hours of Fuji coincides with the U.S. Grand Prix in Austin, but McLaren executive director Zak Brown says he supports Alonso's plans to race at all other rounds of the WEC this year.

"It's no secret that Fernando has wanted to contest the Le Mans 24 Hours. And I think everybody within our organisation appreciates that a motivated, hungry and happy world-class driver such as Fernando is a formidable asset for any team in F1.

"Last year, we came to the joint decision to go racing with Fernando at the Indy 500 rather than at the Monaco Grand Prix. But we've always said that we would consider each opportunity on a case-by-case basis, and we both know that, in 2018, our core priority is success in Formula One.

"Like Fernando, at McLaren we're racers at heart, and our team is built on a brave heritage of competing and succeeding in different forms of the sport. Equally important is the confidence that nothing detracts from our number one goal of Formula One. After proper evaluation, we are satisfied that this campaign does not do that, and that McLaren's best interests prevail."

Toyota has never scored an outright victory at Le Mans and has spent the last six years trying to beat rivals Porsche and Audi. However, in the last two years Audi and Porsche have withdrawn from LMP1, leaving Toyota as the sole manufacturer team in Le Mans' top category in 2018.

Alonso's busy 2018 schedule

Alonso's aspirations to win the Triple Crown blossomed following McLaren's fallow three seasons with Honda power between 2015 and 2017. The McLaren-Honda's lack of competitiveness convinced Brown to back Alonso's Indy 500 aspirations in 2017 and the team agreed to let him skip the Monaco Grand Prix to take part in the famous 500-mile oval race.

Due to dovetailing calendars in 2018, there is only one clash between F1 and WEC this year on October 21 and, as mentioned above, the U.S. Grand Prix will take precedence over the Six Hours of Fuji. However, the new WEC season extends into 2019 as part of the championship's plans to make the season end at its most historic race at Le Mans in future years. That means three rounds of the new WEC season spill into 2019, including the 12 Hours of Sebring on March 16/17, 2019, the Six Hours of Spa-Francorchamps on May 4, 2019 and the 24 Hours of Le Mans on June 15/16.

Below is a list of Alonso's 26 weekends of racing in 2018 (minus the 2019 WEC rounds), including five straight weekends of racing between the Canadian Grand Prix in June and the British Grand Prix in July.

Alonso's 2018 race calendar

• January 27/28 - Daytona 24 Hours (IMSA)

• March 25 - Australian GP (F1)

• April 8 - Bahrain GP (F1)

• April 15 - Chinese GP (F1)

• April 29 - Azerbaijan GP (F1)

• May 4 - Six Hours of Spa Francorchamps (WEC)

• May 13 - Spanish GP (F1)

• May 27 - Monaco GP (F1)

• June 10 - Canadian GP (F1)

• June 16/17 - 24 Hours of Le Mans (WEC)

• June 24 - French GP (F1)

• July 1 - Austrian GP (F1)

• July 8 - British GP (F1)

• July 22 - German GP (F1)

• July 29 - Hungarian GP (F1)

• August 19 - Six Hours of Silverstone (WEC)

• August 26 - Belgian GP (F1)

• September 2 - Italian GP (F1)

• September 16 - Singapore GP (F1)

• September 30 - Russian GP (F1)

• October 7 - Japanese GP (F1)

• October 21 - U.S. GP (F1)

• October 28 - Mexican GP (F1)

• November 11 - Brazilian GP (F1)

• November 18 - Six Hours of Shanghai (WEC)

• November 25 - Abu Dhabi GP (F1)