TOKYO (Reuters) - Mitsubishi Motors (OTC: MMTOF ), a junior partner of Nissan (OTC: NSANY ) Motor, is considering not joining a planned business merger between Nissan and Honda (NYSE: HMC ) Motor, the Yomiuri online said on Friday.

The report came after Nissan and Honda last year said they would begin formal talks on the merger that could potentially create the world's third-largest auto group.

Mitsubishi Motors, in which Nissan is the top shareholder with a 24% stake, was expected to decide by this month whether it plans to take part.