Qwest Communications say some documents that the Securities and Exchange Commission wants to review should remain private.
The SEC is seeking documents from one of Qwest's outside law firms. However, The Denver Post reports Qwest is challenging the request.
Qwest says the documents are covered by attorney-client privilege. The SEC declined comment.
Qwest and law firm partner Jonathan Schiller say the company is cooperating with the investigation.
A settlement between the SEC and Qwest is expected within the next few months.
Qwest hired Schiller's firm last February to take part in the company's internal investigation of its accounting.