Honda and Nissan are understood to have held exploratory talks about a potential merger to help them compete against electric vehicle (EV) makers, particularly in China.
In March, the two Japanese car makers agreed to explore a strategic partnership for EVs.
The firms responded to the BBC with identical statements, which said: "As announced in March of this year, Honda and Nissan are exploring various possibilities for future collaboration, leveraging each other's strengths."
It comes as many car brands grapple with growing competition as the industry shifts from petrol and diesel vehicles to electric, with production in China booming.
Honda and Nissan have not denied the story, which was first reported by Japanese business newspaper the Nikkei, but said it was "not something that has been announced by either company".
The discussions are understood to be in the early stages and there is no guarantee that a deal will be agreed.
"If there are any updates, we will inform our stakeholders at the appropriate time," they added.
The two companies are expected to officially confirm that they have held the talks as early as next week, according to Japanese TV channel TBS.
