WASHINGTON (AP) -- Congressional investigators looking into an outbreak of listeria in cantaloupe that killed at least 30 people last year found that third-party auditors who gave Colorado's Jensen Farms a "superior" rating just before the outbreak largely ignored government guidance on food safety.

A report released Tuesday by the House Energy and Commerce Committee quotes a representative of an auditing company that graded the facility two months before the outbreak as saying that audits are not intended to help clients improve food safety standards. Retailers often rely on such audits to make sure food they buy is safe.

Democrats on the panel asked the Food and Drug Administration to crack down on such third-party auditors, who are often the only outside entities to inspect food facilities.