Medicare has spent $30 million on ambulance rides, but there are no existing records mentioning that patients received medical care at their destination, the place where they were picked up from or other important information. As per a federal audit, released on Tuesday, the mystery ambulance rides belongs to a bigger problem with Medicare payments for transporting patients.

The Department of Health and Human Services' inspector general's office has also discovered that a number of urban ambulance services have received money for an average distance of over 100 miles per ride, which is contrary to a national average of only 10 miles for urban ambulance rides.

It seems like 4 main metro areas have been breeding grounds for ambulance schemes. Philadelphia, Los Angeles, New York and Houston accounted for nearly 50% of the questionable rides and payments.

Medicare has banned appointment of any new ambulance companies in the program in Houston and Philadelphia. The report has recommended a similar approach in certain other places also. In the country, 1 in every 5 ambulance companies had at least some questionable billings.

The report said, "Medicare payments for ambulance transports have increased in recent years, and investigators have uncovered a variety of fraud schemes involving ambulance suppliers".

In the audit, medical claims dating back to the first six months of 2012 were included but as per the inspector general's office the findings have reflected continuing weaknesses in Medicare's efforts against fraud. A Medicare spokesman mentioned that the agency took action after the auditors personally shared their findings in 2014.