Marseille have accused Marcelo Bielsa of holding the club hostage and putting his "personal interests well above those of the institution" following the Argentine's shock resignation.
Bielsa, 60, stunned both Marseille officials and media when he declared he would be leaving the club with immediate effect on Saturday evening in the aftermath of the Ligue 1 defeat to Caen.
He accused the club of wanting to change some details of the contract extension he had previously agreed, and claimed he could no longer work for them with his trust having been broken.
OM countered by releasing a statement in which the board claimed Bielsa had been at fault.
The club said: "The board of Olympique de Marseille did everything to offer the club a coach who was up to that responsibility. But under no circumstances can OM be held prisoner to the demands of someone who places their personal interests well above those of the institution.
"Marseille is imbued with unique values and possesses a sufficiently rich history to refuse to subject itself to the law of a single man."
L'Equipe reported on Monday Bielsa had been irritated during a meeting on Wednesday evening by the attempts of CEO Philippe Perez and lawyer Igor Levin, who had been mandated by OM owner Margarita Louis-Dreyfus, to tinker with the deal he had settled upon some weeks earlier.
The agreement, which ran to 2017, would have increased Bielsa's contract by 25 percent.
Bielsa reportedly criticised Perez and Louis-Dreyfus when he explained himself briefly to the Marseille squad early on Sunday morning.
In a letter to club president Vicent Labrune that Bielsa made available to Argentine media, the coach said: "After a series of meetings we reached an agreement on terms to extend the contract for 2016-17. Over these past few months I have been working and thinking that everything was cleared up and all that remained was for it to be stamped."
Bielsa said he made the letter public "because I feel it is necessary to explain my position in the exact same way I am going to explain it to you.
"Last Wednesday I was called in to meet with the CEO [Perez] and attorney Igor Levin [Louis-Dreyfus' legal representative] and they informed me that they would like to adjust some points of the agreement we had previously reached. It was after this meeting that I reached my decision and I am explaining it and it is definite.
"I don't know if you had approved or ignored it, but I know that I rejected important offers to continue at Marseille because I was very interested in this project. But today I cannot accept this unstable situation brought on by the move to change the terms of the contract.
"So my position is that I will no longer continue working with you. Working together demands a little bit of trust and now we do not have that," Bielsa said.
L'Equipe also claimed the former Argentina and Chile boss had regularly received calls from Mexico where the national federation hopes to install Bielsa as their coach. Last week, Bielsa denied he had any formal contact with the Mexican Football Federation.
Bielsa denied in his resignation that he'd had contact with El Tri.