More than 700 doctors nationwide over-prescribed potentially harmful drugs to elderly and disabled patients in 2009, but were not stopped by Medicare authorities, according to Inspector General report released today.

The audit done by the Inspector General of the U.S. Department of Health and Human Services said the findings "show the need for increased oversight" of Medicare Part D - a program which "provides an option prescription drug benefit to Medicare beneficiaries."

All the drugs ordered by the 736 doctors cost Medicare $352 million.

In 2011, 36 million people were enrolled in Part D, according to the report. It has been under scrutiny since 2009 for questionable billing. A report from September 2012 showed Part D inappropriately paid $25 million for refills in 2009. Another one form January 2013 showed it paid $1.2 billion to patients with invalid prescriber names.

The review studied 87,000 general-care physicians in both urban and suburban areas. More than 2,200 of these doctors had records that stood out, due to triggers such as high prescriptions per patient or an excessive amount of painkiller prescriptions. 736 of these doctors were flagged as "extreme outliers" - or doctors whose patterns of excessive prescriptions may not have been "legitimate or necessary."

Overall, the average doctor in the findings wrote 13 prescriptions per patient - more than double the national average of 6 prescriptions per patient.

Go here for the full report.