Where Factory class should be placed on in a MVC application?

I'm learning MVC pattern and building a simple java application without any framework, just building the package structure by myself in order to understand and practice the MVC concepts.
I have the packages: model, view and controller so far. So, I have a Factory class to build some objects (part of the model) and I'm not sure in which of these packages place the factory class. I'm sure is not part of view :), so should it be part of model or controller? Or may be is it correct to have other package to place it?