Autosport exclusively revealed on Monday that the Frenchman had left his non-executive director and advisory role with the French car manufacturer as part of a management overhaul being undertaken this winter.
After taking to social media to express his disappointment at the way news of his departure had been made public, Prost opened up to French newspaper L’Equipe and discussed the reasons for his exit.
Prost said that he had felt increasingly isolated throughout 2021 following the arrival of Rossi, and that had left him unhappy about his position within the team.
“The 2021 season was very disturbing to me as I felt that those who had been here for a long time had to go,” he explained.
“I accept change, as you don't have to always do F1 the same way. You can do it differently, and that's what was done throughout last year. But for me, it has become too complicated.
“I wasn't involved in decision making any more, I sometimes disagreed – completely – but I had to keep conveying the official word.
“Even as a member of the board, I found out about some decisions at the last minute. I may not be listened to, but I should at least be informed in time. It's a matter of respect. Relationships have become more and more complicated, I could feel a lot of jealousy.”
Prost said that Rossi, who is working on a new management structure, had made it clear to him that he no longer wanted an advisor.
“Laurent Rossi wants to be alone, not to be annoyed by anyone,” added Prost. “He actually told me himself that he no longer needed an advisor.
“It was in Qatar, but he still offered me a contract in Abu Dhabi, which I refused. I still must say that I believed – and still do – in this ambitious project which has incredibly boosted motivation in the group.
“However, there is now a real drive to sideline a lot of people. Laurent Rossi wants all the spotlight. What I'm interested in is the challenge of being in a team, being listened to and involved in some decisions.
"I was very much in the background on purpose, but I discreetly had some influence despite all the disagreements I kept to myself.”
Prost’s comments to L’Equipe come after he made some pointed remarks on Instagram about the way Alpine had handled news emerging about his departure.
“I am very disappointed how this [news] has been announced today!” he wrote. “It was agreed that we would announce together with @alpinef1team! No respect sorry!
“I have refused the offer made to me in Abu Dhabi for the 2022 season because of a personal relationship and I was right! To the Enstone and Viry team I will miss you”
Prost’s exit from Alpine comes amid Rossi restructuring the team in a bid to help it move further up the grid.
The team announced earlier this month that executive director Marcin Budkowski had left with immediate effect, and it is expected that former Aston Martin team principal Otmar Szafnauer will step in as new team principal.