(Adds revenues, context)
MEXICO CITY, July 28 (Reuters) - Mexican national oil company Pemex said on Thursday its losses narrowed in the second quarter, marking its 15th straight quarter in the red.
The loss at Pemex shrunk more than 1 percent to 83.5 billion pesos ($4.6 billion) from 84.6 billion pesos in the year-ago quarter, helped by lower costs and taxes.
Revenue in the April-June period fell more than 17 percent to 255.7 billion pesos from 308.9 billion pesos a year earlier, the company said in a filing with the Mexican stock exchange.
$1 = 18.2575 pesos at end of June Reporting by Michael O'Boyle and Joanna Zuckerman Bernstein Editing by W Simon