UPDATE 1-United Continental posts wider loss as revenue weakens

* First quarter adjusted loss $1.33/shr vs estimate loss $1.35/shr

* Unit revenue, yield fall

(Adds estimates comparison)

April 24 (Reuters) - United Continental Holdings Inc posted a wider quarterly loss on Thursday as expenses increased and revenue fell, hurt in part by flight cancellations tied to winter storms.

The first-quarter loss came to $609 million, or $1.66 a share, compared with $417 million, or $1.26 a share, a year earlier.

Adjusted for items including merger integration and severance costs, the loss was $1.33 a share, compared with a loss of $1.35 a share expected by analysts on average, according to Thomson Reuters I/B/E/S.

Quarterly revenue fell 0.3 percent to about $8.7 billion, but operating expenses rose 0.7 percent to just over $9 billion. Though fuel costs fell 4.0 percent, expenses tied to salaries and airport landing fees rose.

Passenger revenue per available seat mile, an important airline measure, fell 2.0 percent to 12.91 cents. Average yield, a measure of the average fare paid per mile flown, fell 2.0 percent to 15.92 cents.

(Reporting by Karen Jacobs in Atlanta; Editing by Jeffrey Benkoe)