UPDATE 1-Alpha Natural operating loss widens, revenue slides

* Loss before items 19 cents/shr vs year-ago loss 9 cents

* Revenue falls to $1.56 billion from $2.07 billion

Feb 14 (Reuters) - Alpha Natural Resources Inc, a major U.S. coal producer, reported a wider quarterly operating loss on Thursday as revenue tumbled 25 percent amid weak coal prices and production cuts.

The company, which curbed output last year to control costs in a tough market, said it may "further adjust" its operations to reflect industry conditions.

Alpha Natural is the largest U.S. supplier of metallurgical coal, used in making steel, and also produces thermal coal, used in power stations. Low prices battered U.S. coal produces in 2012.

In September, Alpha Natural said it would cut about 1,200 jobs, or 9 percent of its work force, idling mines in Virginia, West Virginia and Pennsylvania, and reducing production in the Powder River Basin coal-rich region of eastern Montana and Wyoming.

For the fourth quarter, Alpha's net loss was $128 million, or 58 cents a share, compared with a loss of $793 million, or $3.62 a share, a year earlier. Revenue fell to $1.56 billion from $2.07 billion.

The company took a charge of $188 million to write down the value of assets, which it said was based on conditions in the coal market and lower expected future production, especially of thermal coal.

Excluding the impairment and restructuring charges and other special items, its adjusted loss was $41 million, or 19 cents a share, compared with a loss of $19 million, or 9 cents a share, a year earlier.