The Big Four audit firm's comments came in a 2007 inspection report by the Public Company Accounting Oversight Board, released Monday, which found fault with eight public-company audits conducted by Deloitte.

Deloitte contested inspectors' conclusions in two audits and said it undertook additional work on the remaining six audits where inspectors faulted its efforts.

"Deloitte & Touche is dedicated to conducting the highest quality audits," spokeswoman Deborah Harrington said in a statement Monday. "The observations and comments from the inspectors will continue to be a key contributor in our efforts to improve our audit execution, methodologies and policies."

Inspectors said that, in one case, Deloitte failed to detect errors that "significantly overstated" the potential tax benefits to an audit client. In a written reply, included in the inspection report, Deloitte said the error didn't affect the client's balance sheet or cash flows and wasn't large enough to warrant inclusion in the public inspection report.

In another case, inspectors said Deloitte failed to include evidence showing it had done work to resolve differences in the amount recorded by the client for promotional activity and its estimated promotional allowance.

"The engagement team addressed the testing of promotional allowances during the audit and we believe the procedures performed and conclusions reached were appropriate," Deloitte wrote in a May 29 letter, included in the 2007 report. It added that, in its view, since "no further documentation or procedures are considered necessary," the matter shouldn't have been raised by inspectors in the public portion of their annual report.

Only a portion of the findings are publicly released each year.

Inspectors based their 2007 findings on field work from May through November 2006 at Deloitte's national office and 20 of its other U.S. offices. In eight cases, involving unnamed Deloitte clients, inspectors said it appeared that Deloitte had erred by issuing audit findings without sufficient evidence to support its opinion on the company's financial statement. Inspectors had identified 17 problem audits in their 2006 report on Deloitte, up from 8 in 2005.