But it also says such a co-operation would not become an alliance.
Mitsubishi sold its 7.93% stake in Proton in 2004, but still supplies parts.
The Japanese carmaker could cooperate with Proton in the areas of environmental and fuel economy technologies as it would be difficult for a single company to develop such advanced technologies on its own in the short-term, Mitsubishi president Osamu Masuko said.
He said that while Mitsubishi Motors is not currently in talks with Proton on any new ties, it would consider any requests from the Malaysian automaker.
An advisor for Proton said investors have lost confidence in Proton following Volkswagen's decision to pull out of partnership talks with Proton on January 12, resulting in a steep fall in Proton's share price.