TOKYO — The cracks in the world’s largest auto alliance grew wider on Monday, as Nissan Motor condemned as “most regrettable” a decision by its French partner, Renault, to withdraw support for the Japanese automaker’s efforts to overhaul its governance.

The message signals a new low in the relationship, and reflects the fallout from the collapse last week of a proposed merger between Renault and Fiat Chrysler that would have created one of the world’s biggest carmakers. Nissan’s hesitance to agree to the deal was a contributing factor in the breakdown.

In a statement on Monday, Nissan’s chief executive, Hiroto Saikawa, said he had received a letter from Renault saying that the French company intended to abstain from a shareholder vote to adopt the governance overhaul. The measures were intended to address problems with the company’s management that came to light after the November arrest of Carlos Ghosn, the former chairman of the two companies and the overall alliance.

“Nissan finds Renault’s new stance on this matter most regrettable, as such a stance runs counter to the company’s efforts to improve its corporate governance,” Mr. Saikawa said in the statement.