The proceedings were begun as a result of indications that Google had that it had failed to be clear about what it does with user data, may be processing a "disproportionate" amount of such data and holding onto it for an "undetermined or unjustified" period of time, AEPD said.
The launching of the sanction proceedings comes after investigations revealed the possible commission of six infractions - five of them serious and one minor - of the Data Protection Law.
"We're completely committed to the authorities linked to this process and we will continue to be," Google said.
Google Spain and Google Inc., if the five serious infractions are confirmed, would face a fine of between 40,001 euros ($52,932) and 300,000 euros (about $397,000) and between 900 euros ($1,191) and 40,001 euros ($52,932) if the minor infraction holds up.
In April, the AEPD agreed to begin this investigation within the framework of a coordinated action with the data protection authorities in Germany, France, the Netherlands, Italy and Britain.