Satellite mogul Charles Ergen has offered to boost the capital and restructure the debt of Sirius XM Radio Inc, which has been preparing for a possible bankruptcy filing, newspapers reported.

Ergen has offered to inject several hundred million dollars of capital into the satellite radio company, though his plan does not involve buying out existing shareholders, the Wall Street Journal said, citing people familiar with the matter.

On its Web site, the New York Times cited people close to the company as saying Sirius has been working with advisors on a possible Chapter 11 filing, which could put pressure on satellite TV company EchoStar Corp, which is headed by Ergen and reportedly holds a substantial amount of Sirius XM debt.

Sirius and EchoStar could not be immediately reached early on Wednesday for comment, the Journal report.

On Tuesday, Sirius officials had not responded to several telephone and email messages, and EchoStar declined comment.

Sirius's total debt load is about $3.25 billion, the Journal said, and its market value has plummeted by more than 96% since last July.

Sirius has been working with restructuring expert Joseph A. Bondi of Alvarez & Marsal and bankruptcy lawyer Mark Thompson of Simpson, Thacher & Bartlett to help prepare a Chapter 11 filing, the New York Times reported, adding that a filing could come within days.

A Simpson, Thacher spokeswoman declined comment, and Bondi was not immediately available for comment.

Sirius has also been working with investment bank Evercore Partners, the Times said. Evercore could not be reached immediately.

Last week, the Wall Street Journal reported that EchoStar holds about $400 million of Sirius XM debt and the satellite radio company led by Mel Karmazin is scrambling to raise $175 million by a Feb. 17 payment date to fend off a possible takeover threat and avoid default.

Sirius XM has nearly $1 billion in debt due this year, prompting analysts to doubt its future given the sluggish credit market and a steep drop in car sales, the biggest source of new satellite radio subscribers.

Sirius XM shares saw a 23.8% increase in short interest from mid- to late-January -- the biggest increase on the Nasdaq, indicating that more short sellers were trading the stock.

Short sellers borrow shares and then sell them, waiting for the stock to fall so they can buy the shares back at the lower price, return them to the lender, and pocket the difference.

Sirius shares closed Tuesday's session 3.5% higher at 11 cents on the Nasdaq.