Justin Langer reportedly told Cricket Australia that he was quitting as head coach due to a lack of support from senior players, support staff and the board.
Langer resigned with immediate effect on Saturday and, in a copy of his resignation letter obtained by The Australian, he explains why he decided to reject the offer of a short-term contract extension.
In the letter, which was reportedly sent to Cricket Australia CEO Nick Hockley, Langer said he felt it was "in everyone's best interests" for him to walk away and apologised if he came across as "too intense".
He also said he felt he was "going out on a high" after leading Australia to their first T20 World Cup win, a dominant Ashes victory and the number one spot in the ICC's Test rankings.
"Last night I was offered a short-term contract until the end of the T20 World Cup in Australia, with the sentiment of 'going out on a high'," Langer reportedly wrote.
"After careful consideration I have decided not to accept this contract renewal, and as a result I believe it is in everyone’s best interests for the Australian cricket team to begin the next chapter immediately.
"If media reports are correct, several senior players and a couple of support staff don’t support me moving forward, and it is now apparent the CA board, and you Nick, are also keen to see the team move in another direction. I respect that decision.
"My life has been built on values of honesty, respect, trust, truth, and performance and if that comes across as 'too intense' at times, I apologise.
"In terms of 'going out on a high', I am blessed to have been a part of a T20 World Cup-winning squad, an Ashes winning squad, watched the Test team rise to #1 ranked team in the world today, been selected as the Wisden Coach of the Year and been elevated to the Australian cricket Hall of Fame; all this in the last five months.
"I am grateful that today, I am going out on a high."