DENVER -- Qwest Communications International Inc., already under investigation for its accounting practices, expects to restate financial reports for 2000 and 2001 because an internal analysis found accounting errors.

In early trading Monday, the company's stock fell about 20 percent to $1.20 a share on the New York Stock Exchange.

Officials said during a conference call with investors Monday that they could not discuss some information because of a federal investigation into some transactions and accounting practices.

Company officials declined to estimate how the errors would affect the books or when a restatement of revenue would be completed.

Company officials say the errors were related to telephone services and sales of optical capacity and equipment.

The Denver-based telecommunications company said it will file a restatement after it completes an analysis of its accounting practices.

Chief Executive Officer Richard Notebaert says restating the earnings will likely take months, and will likely miss the Aug. 14 deadline set by the Securities and Exchange Commission for the nation's biggest companies to certify the accuracy of their financial statements.

"If accounting errors were made, they will be corrected and they will be disclosed. The public will be fully informed," Notebaert said Monday. "If an individual violated company policy, appropriate action will be taken. Internal practices are being and will continue to be enhanced."

Qwest stock has tanked in recent months -- a big concern to investors, retirees and current employees whose retirement accounts are heavily invested in the stock. In March 2000 the stock reached a high price of $64. On Friday, July 26, the stock closed at $1.50.

The embattled company is about $26 billion in debt.

Qwest's accounting practices are also under federal investigation.

The SEC is investigating Qwest's fiber-optic capacity swaps with Global Crossing, Enron and others in 2000 and 2001.

In terms of its fiber-optic capacity sales, Qwest booked most of the revenue from the sales in the one year it was sold, as opposed to spreading out the revenue over the life of the deal, as it the practice of other telecoms.

In the cases of the swaps, the SEC is investigating whether they were sham deals meant to boost revenues and earnings.

Arthur Anderson was the company's auditor during the time in question.

Qwest's announcement comes as the federal government is pledging a thorough crackdown on corporate misdeeds after a series of scandals at major companies eroded investor confidence in Wall Street.