Negotiations for a tie-up between Renault and Fiat Chrysler (FCA) collapsed in June, with Renault's chairman blaming the French government for blocking a vote on the deal that would have upended the global automotive industry and created the world's third-largest car-maker.
The French government has denied the allegation, while Nissan has characterised its relationship with Renault as unequal and said the French had kept the Japanese wing in the dark over merger plans with FCA.
Citing emails and sources close to the companies, The Wall Street Journal on Friday reported that Nissan is now asking Renault to reduce its 43 percent stake in the Japanese automaker.
Nissan controls 15 percent and has no voting rights in Renault, which is also part-owned by the French government.
A rebalanced relationship would help ease some of the tensions between the two companies and relieve Nissan's reluctance to back the merger with FCA, the paper said.
A draft agreement on restructuring the relationship could come as early as September, the Journal reported.
Any agreement would need the green-light of the French state, which owns 15 percent of Renault.
French President Emmanuel Macron said in late June that he wouldn't consider any changes to the two companies' structure.