MADISON, Wis. -

The president of the University of Wisconsin System said he's embarrassed by a recent audit finding the system overpaid for health insurance premiums and pension contributions by nearly $33 million over the last two years.

A Wisconsin State Journal report said President Kevin Reilly has promised to hire an independent auditor to figure out what went wrong.

The Legislative Audit Bureau released a report Thursday outlining the overpayments.

The UW System recovered all $17.5 million in overpaid pension contributions to the Wisconsin Retirement System in 2011. But so far only $2.4 million of the $15.4 million in overpayments on employee health insurance premiums has been recouped.

Reilly said officials will identify how and why the errors occurred, and make sure they don't happen again.