Nissan Motor Co. could find itself chained to a much bigger gorilla as Renault SA and Fiat Chrysler Automobiles NV proceed with a plan to forge closer ties. The Japanese carmaker doesn't like it but may not have much of a choice.

Fiat Chrysler announced a merger plan Monday with Renault, Nissan's partner of two decades, that could create the world's third-biggest automaker. While the pair isn't seeking a merger with Nissan for now, they plan to eventually invite Nissan and Mitsubishi Motors Corp., Renault's existing global alliance partners, to join forces, sources said.

Nissan isn't involved in talks between the two European car companies and doesn't view an extensive deal between them as a positive development, people with knowledge of the matter said. Nissan isn't interested in a scenario that pursues car sales for the sake of volume, the sources said, asking not to be identified because Nissan's stance isn't public.