Fernando Alonso is leaving F1 because of his "strong character".

That is the view of the Spaniard's former Renault teammate, Jarno Trulli.

Alonso, 37, is quitting F1 to race at the Indy 500, Le Mans and some other "iconic" races in 2019, but is not ruling out a return for 2020.

"Alonso was a great teammate, but he had a strong character," Italian Trulli told Omnisport.

"In the team it was not easy to manage, not only as a driver but as a person. That has been demonstrated during his career," he added.

"Unfortunately, his character led him to a situation in which he had no opportunity, despite being one of the best.

"He did not have a competitive car to stay in formula one, so he has been obliged to retire, even though that time does come for everyone," Trulli said.