Japanese automakers Nissan Motor Corp. and Honda Motor Co. confirmed Wednesday that they are discussing closer collaboration but denied reports they have decided on a merger.

Nissan's share price soared nearly 24% in Tokyo after reports citing unnamed sources said it might merge with Honda to form the world's third-largest automaking group. Honda's share price fell as much as 3%. Nissan alliance member Mitsubishi Motors Corp. is also part of the talks.