How to disable mipmaps?

I'm making a game that uses a texture atlas system, buty the textures are very small as the art-style calls for flat colours, no real texture detail.

However, when the textures are rendered from afar, there are artefacts, I believe to be caused by some automatic mipmaps made of my textures. The screen shot is of the problem, so if I am wrong in my assumption here, feel free to say.

As you can see, there is a lot of orange being added to the scene, when the texture should be flat green.

Is there any way of disabling mipmaps globally? Or will I have to define that I do not want mipmaps when generating my texture atlas, if so, how?

If you need any code samples provided I will happily provide!