CHICAGO - United Airlines' parent company reported a wider loss of $664 million for the fourth quarter Thursday and a narrower $1.6 billion deficit for the full year, blaming high fuel costs and continued pressure on fares.

It is the 18th straight quarterly loss for UAL Corp., which is trying to emerge from 26 months in Chapter 11 bankruptcy.

The net loss for the final three months of 2004 amounted to $5.73 per share and was larger than the loss of $476 million, or $4.33 per share, for the same period a year earlier. Excluding special items, the quarterly loss was $553 million, or $4.77 a share.

Revenues for the fourth quarter rose 5 percent to $4 billion, from $3.8 billion.

The company said its fuel costs for the fourth quarter spiked nearly 58 percent to $842 million.

But United's $1.6 billion loss for the year was smaller than the net loss of $2.8 billion in 2003. United lost $3.21 billion 2002, when heavy losses forced it to make the largest bankruptcy filing in aviation history.

"United has made good progress with more cost reductions already underway," said Glenn Tilton, UAL's chairman and CEO, in a statement. "But ... as this quarter shows without question, we have more work to do."

United is seeking $725 million in additional savings on labor costs, atop $2.5 billion in cuts it pushed through in 2003, in its bid to exit bankruptcy. The company has reached tentative labor agreements with five of its six unions, although most of those still must be approved by members.

Voting on the contract ratification from the company's mechanics is expected to end Friday. Balloting is set to close Monday for United's flight attendants' and pilots' unions.