Hundreds of claims made by TTC employees are being examined as part of an investigation into an alleged benefits scam, Toronto's auditor general says.

In a report issued Friday, Auditor General Beverly Romeo-Beehler said more than 600 employees of the city agency issued claims through an organization involved in a fraud investigation.

"The total number of improper or fraudulent claims is still to be determined," the report said.

In an earlier version, the auditor general erroneously reported that 600 employees were under investigation, but later corrected the wording.

The edited report clarifies that, while 600 submitted claims, it is not yet known how many of the claims were fraudulent, if any.

The total benefits paid out to TTC employees for services claimed was $5.1 million, the report said.

The investigation began after the TTC received a confidential tip last year, that some claims made to a Wilson Heights orthotics business were fraudulent.

Police allege the owner and two employees of the orthotics clinic convinced TTC employees to submit benefits claims for services and devices that were never provided.

The TTC has dismissed a dozen people in connection with the ongoing investigation.

In a statement Friday, TTC spokesperson Brad Ross said that the agency is conducting an investigation parallel to one operated by Toronto police.

"As our investigation continues, we dismiss employees where evidence of fraud is clear," he said.