DENVER -- Qwest Communications admitted Wednesday that it is under investigation by the United States attorney's office in Denver.

In a statement, Denver-based Qwest said it was informed of the investigation Tuesday. Last week, Qwest denied a published report in the Wall Street Journal that it was the subject of a Justice Department probe.

The U.S. Attorney's office did not disclose the subject matter of the investigation.

Qwest said it plans to fully cooperate with the U.S. Attorney's office.

Jeff Dorschner, a spokesman for U.S. Attorney John Suthers, confirmed Wednesday that an investigation is underway but would not say when it started or what is being investigated.

Last week, the company denied a report in The Wall Street Journal that Qwest was being investigated by the U.S. attorney and the Federal Bureau of Investigation.

In the past year, Qwest has faced a Securities and Exchange Commission inquiry into its accounting practices, a downgrade of its credit rating to junk status and a sinking stock price. Longtime chief executive officer Joseph P. Nacchio resigned last month.

Qwest, which was once part at the Bell System under AT&T Corp., is the local phone company for 14 states extending from Minnesota west to Washington and southwest to Arizona and New Mexico.

In morning trading on the New York Stock Exchange, Qwest shares were down 80 cents, or 30.8 percent, to $1.80.