UPDATE 1-Chile July copper output down 5.5 pct vs year ago

(Adds molybdenum output)

SANTIAGO, Aug 28 (Reuters) - Chile, which provides around a third of the world's copper, produced 430,361 tonnes of the metal in July, down 5.5 percent from the same month last year, the government said Thursday.

Output from January through July this year fell 2.3 percent from the same period last year to 3,128,299 million tonnes.

Production of molybdenum, a metal that often occurs together with copper and which is used to strengthen steel, fell 25.7 percent in July to 2,947 tonnes.

For the year-to-July, molybdenum output was down 22.2 percent. (Reporting by Antonio de la Jara; Editing by John Picinich)