Six of the 12 host stadia have failed to meet the December 31 deadline while delays have also affected work on hotels, airports and roads.
Blatter pointed out that Brazil has had seven years since it was awarded the tournament - previous hosts only had six years or even less time.
Asked if World Cup hosts realised the scale of work involved, the FIFA president told Swiss newspaper 24 Heures: "No. Brazil has just found out what it means and has started work much too late. No country has been so far behind in preparations since I have been at FIFA even though it is the only host nation which has had so much time - seven years - in which to prepare."