UPDATE 1-Barrick reports big loss on impairment charge

(Adds gold reserves, cost forecast)

TORONTO, Feb 13 (Reuters) - Barrick Gold Corp reported a big fourth-quarter loss on Thursday as it took another impairment charge, cut its gold reserve estimate by 26 percent and said a key cost measure might rise this year.

The world's largest gold miner forecast all-in sustaining costs of between $920 and $980 to produce one ounce of gold for 2014, up from $915 in 2013.

The Toronto-based company slashed estimated gold reserves to 104.1 million ounces from 140.2 million ounces a year earlier. About half the decline came because Barrick used a lower gold price assumption of $1,100 an ounce, down from $1,500.

The company cut its mine life estimate for Porgera in Papua New Guinea to nine years from 13 years, citing a new plan that focuses on higher-quality underground ore. It took a $595 million impairment charge on Porgera.

In total Barrick took $2.82 billion in after-tax impairment charges. They include $896 million for its troubled Pascua-Lama project, which was indefinitely suspended in the autumn.

The company said its net loss had narrowed to $2.83 billion, or $2.61 a share, from $3.01 billion, or $3.01 a share, a year earlier, when it also took a large impairment charge.

Revenue dropped to $2.93 billion from $4.15 billion as the price of gold fell sharply.

(Reporting by Allison Martell; Additional reporting by Euan Rocha; Editing by Lisa Von Ahn)

((allison.martell@thomsonreuters.com)(+1 416 941 8196)(Reuters Messaging: allison.martell.thomsonreuters.com@reuters.net))

Keywords: BARRICK RESULTS/