CHICAGO, Dec. 1 -- United Airlines and its mechanics union met today as the nation's second-largest carrier pressed for hundreds of millions of dollars in cost cuts it says are necessary to keep it out of bankruptcy.

The mechanics last week rejected a proposed package of wage and benefit cuts that United's parent, UAL Corp., said were necessary to get a $1.8 billion federal loan guarantee that would keep it out of bankruptcy court proceedings.

United spokesman Jeff Green confirmed the meeting, but said the airline would not discuss any aspects of the talks. Machinists union spokesman Joseph Tiberi said neither side would comment while talks continued.

The meeting came a day after the airline's 24,000 flight attendants agreed to $412 million in wage concessions. However, that deal and other cost-cutting agreements accepted by United's pilots and other employee groups expire Dec. 31 unless the mechanics sign on to the plan.

United is seeking $5.2 billion in company-wide labor cuts over 51/2 years. The mechanics' proposed share is believed to be $600 million to $700 million.

The cash-strapped airline also must decide whether it can make a $375 million debt payment Monday, although under a grace period it could push that deadline back to Dec. 16.

Its cash reserves are believed to be about $1 billion and on a pace to run out this winter.

A ruling is expected soon on United's application for a $1.8 billion federal loan guarantee, which United says it must have to obtain $2 billion in private loans. Without the loan guarantee, United has said it would likely have to file for Chapter 11 bankruptcy protection.

United has been struggling since the 2001 attacks. It has reduced service and laid off 20,000 workers because of the weak economy and reduced spending by business travelers. On Friday, speculation that United was headed into bankruptcy sent shares of UAL tumbling 33 percent, to $2.45 a share on the New York Stock Exchange.

A bankruptcy filing is likely to have no immediate effect on passengers, since United has said it would continue flying its normal schedule. But the prospect of such a filing has raised concerns among some of the other unions that represent United workers, which fear that a bankruptcy court would order even more severe concessions.