Scandal-hit Japan Post Co. improperly sold around 104,000 insurance policies issued by U.S. partner Aflac Inc., sources close to the matter said Wednesday, bringing the total for inappropriately sold policies to 287,000 nationwide.

As the debacle expands, the problems are being blamed on the postal and financial behemoth's failure to update its customer data management system, the sources said. Japan Post said the problem will take until October to fix.

The actions of Japan Post, which sells Aflac policies at post offices nationwide, resulted in customers becoming temporarily uninsured and or being double charged for a one-year period that ended in May this year, the sources said.