A Global Crossing vice president questioned his superiors about aggressive accounting practices less than six months before the telecommunications provider filed for bankruptcy, the company confirmed Wednesday.

Roy Olofson, vice president of finance at the time, sent a letter to the firm's top lawyer in August, advising him that the company was using misleading accounting techniques, specifically inflating revenue and cash flow, to enhance the appearance of results.

Olofson asked then-general counsel Jim Gorton to exclude chief financial officer Dan Cohrs and Olofson's own boss, Joe Perrone, from any investigation.

Gorton left the company just days after receiving Olofson's letter and Olofson was laid off three months later.

Global Crossing said Olofson's charges were baseless and that Gorton's departure was unrelated.

"This is a situation we are very familiar with, which has been thoroughly investigated both internally and externally and is without merit," said Dan Coulter, a company spokesman.

Global Crossing also said Olofson threatened to make his allegations public if the company didn't pay him to keep quiet.

Olofson's lawyer, Brian Lysaght, did not immediately return calls seeking comment.

Global Crossing, which spent billions of dollars over the last five years building a global fiber optics network, filed for bankruptcy protection on Monday. The Beverly Hills-based firm listed $12.3 billion of debt and $22.4 billion of assets, in what amounts to one of the largest bankruptcy cases in U.S. history.

Craig Shere, a telecommunications analyst for Standard & Poor's in New York, said that Global Crossing's accounting practices were particularly aggressive, even in an industry known for pushing accounting boundaries.

In one instance, the company bought some $300 million of network space from its own customers.

That swap led Shere to believe one of two things: either there was insufficient demand for capacity, or the demand was there, but customers couldn't pay for it.

Shere compared the practice to failed Internet companies booking millions of dollars of revenues for running each other's ads.

"It left me kind of queasy," he said.

Other debt rating firms agreed that Global Crossing used aggressive accounting practices.

Egan-Jones Ratings Co., a Wynnewood, Pa., firm that provides credit ratings and research for institutional investors, downgraded Global Crossing debt to junk status in late September.

"The company had a need to show revenues and show a profit as early as possible and therefore had every incentive to push the envelope as far the accounting practices are concerned," said Sean Egan, managing director.

But Randolph Beatty, dean of accounting at UCLA's Marshall School of Business, warned against developing "hindsight bias" toward Global Crossing.

He said asset swaps between a company and its customers can be perfectly legitimate in many cases.