There is a "warm atmosphere" within the Renault-Nissan alliance and a deal regarding its future will be announced "in due time," the French carmaker's chairperson said on Tuesday.

The auto giants are in talks over a potentially drastic reshaping of their sometimes rocky 23-year union.

Nissan currently owns 15% of Renault, but Renault owns 43% of Nissan – a power imbalance that has long bothered the Japanese company.

While the discussions are behind closed doors, a source close to the matter told Agence France-Presse (AFP) that they involve a rebalancing of the cross-shareholding arrangement and a possible Nissan investment in Renault's new electric vehicle venture.

But concerns over issues such as the sharing of EV intellectual property have delayed an announcement, according to the source.

On Tuesday, Renault chair and alliance boss Jean-Dominique Senard sought to reassure reporters in Tokyo that the "warm atmosphere" within the alliance "bodes well" for its future.

"Confidence and trust have never been as high" between the pair and their smaller partner Mitsubishi Motors since he took charge of the three-way alliance almost four years ago, Senard said.

Any deal on a new shareholding agreement will be unveiled "in due time," he added after giving a speech at an international financial forum.

Renault and Nissan joined forces in 1999 when the French company rescued the Japanese carmaker from bankruptcy.

Relations between the pair have not always been smooth, however, and were thrown into further disarray by the shock 2018, arrest of tycoon alliance boss Carlos Ghosn.

This month, Renault announced it will split its operations in two – a new electric vehicle business called Ampere and a separate subsidiary for petrol, diesel and hybrid cars that will pair up with China's Geely.

Renault has yet to outline the part that Nissan will play in the new electric division, but its joint venture with Geely is reportedly raising questions in Japan about future technology transfers to the Chinese carmaker.