(Adds detail on businesses, reason for lower profit)
MEXICO CITY, April 15 (Reuters) - Mexican conglomerate Alfa said on Tuesday its first-quarter profit fell 35 percent, hurt by lower margins and an inventory charge at its Alpek petrochemicals unit as the value of raw materials for its polyester businesses fell sharply.
The company, which also manufactures car parts and refrigerated foods, said profit fell to 1.698 billion pesos ($130 million) from 2.631 billion pesos a year earlier.
Alfa said first-quarter revenue rose 3.46 percent to 51.5 billion pesos, helped by higher sales from car-parts business Nemak, cold-foods business Sigma and its phone company Alestra.
Alpek saw a 2 percent drop in sales volume and 14 percent lower revenue from the year-earlier quarter, as margins for its polyester products fell.
Shares in Alfa closed up 1.02 percent at 34.67 pesos. Shares in Alpek closed up 0.23 percent at 22.16 pesos.
$1 = 13.06 pesos at end March Reporting by Elinor Comlay