Brendon Hartley has issued his first comments since his exit from Toro Rosso's Formula 1 team for 2019 was confirmed, saying he has "unfinished business" in the sport.

Toro Rosso announced on Monday that Alexander Albon would be joining the team next year alongside Daniil Kvyat, leaving Hartley without a seat after just one full season with the team.

Driver Ratings - Abu Dhabi GP

In a message posted on his Twitter account on Tuesday, two-time FIA WEC champion and 2017 Le Mans winner Hartley expressed his pride over his efforts in F1 and thanks for the support he has received in the wake of Toro Rosso's announcement.

"I left the circuit on Sunday with my head held high. I’m very proud of my story and journey so far, but am left feeling I have unfinished business in F1," Hartley said.

"For the moment that has been put on hold. I’ve hit speed bumps before and I am a strong believer that tough situations make you stronger, it also helps that I have a great NZ support crew, family, friends and wife.

"I also want to thank my trainer Rich and almost all of the 500 strong Toro Rosso staff who I have stood beside and have enjoyed working with this season, all of the engineering team, the mechanics, marketing, PR, logistics, hospitality crew, factory staff and of course all at Honda racing.

"I really do appreciate the support I have received from fans across the globe this year, I still have plenty more pages to write in my story and will make the most of the opportunities in the next chapter."

Hartley said in Abu Dhabi last weekend he was yet to consider any options outside of F1 for 2019, having stressed that he had a valid contract to race with Toro Rosso next year.

Outside of his sports car racing interests, the New Zealander had been set to move into IndyCar for 2018, only to then receive a shock call-up from Toro Rosso in F1.