Deloitte & Touche LLP repeatedly failed to support assumptions in audits examined in a 2007 inspection, the Public Company Accounting Oversight Board said in the first public report of unresolved deficiencies involving one of the so-called Big Four accounting firms.

The firm's quality controls and independence systems give “cause for concern,” the PCAOB said in its report, which was released today. The Washington-based nonprofit, created in 2002 to oversee audits of public companies after the collapses of Enron Corp. and WorldCom Inc., gives audit firms at least a year to fix deficiencies and only releases the reports in cases where auditors fail to make sufficient improvements.

“These deficiencies may result, in part, from a Firm culture that allows, or tolerates, audit approaches that do not consistently emphasize the need for an appropriate level of critical analysis,” the PCAOB said in the Deloitte report, which didn't name the clients involved in the cited audits.