That could very well have been misinformation on Itachi's part in an attempt to get Sasuke to distrust Madara.

I'm thinking Itachi tried to put blame on Madara since he was still loyal to Konoha, even after joining Akatsuki, and he wanted to make sure Sasuke didn't take Madara's side and oppose Konoha for the sake of revenge.

Sheesh, 2,500 posts...do I get a medal yet?