(Adds details on upcoming joint ventures, taxes)
MEXICO CITY, Oct 28 (Reuters) - Mexico's state-run oil company Pemex reported a steep third-quarter loss on Wednesday of 167.5 billion pesos ($9.9 billion), well over double the 60 billion pesos loss in the same period last year, hurt by low oil prices and a weaker Mexican peso.
It was Pemex's 12th consecutive quarter in the red.
Pemex said crude output for the quarter was down 5.5 percent, and natural gas production dropped nearly 1.7 percent.
Crude exports jumped 10 percent from a year earlier to total 1.206 million barrels per day (bpd), but the crash in crude prices offset the higher export volume.
The average price of Mexico's mix of crude exports for the quarter was $41.75 per barrel, down nearly 54 percent from the same quarter last year.
Total sales for the July-September period were 313 billion pesos, with earnings before earnings before interest, tax, depreciation, and amortization (EBITDA) 119 billion pesos, Pemex said in a statement.
Pemex said it had reached a deal with its union to reduce the company's massive pension liability, much of which the government will absorb.
The company did not detail how it will reform pension benefits for current and future employees, a condition set by a major energy reform finalized last year. It said specifics would be announced in the next few days.
Executives said in an earnings call the company hopes to boost near-term output via more than a dozen first-ever joint ventures with private producers expected to be signed next year.
Pemex, struggling to turn around a decade-long slump in crude oil output, said production averaged 2.26 million bpd during the quarter.
Pemex imports about half the gasoline consumed in Mexico, and the weakening Mexican currency added to those peso costs.
Mexico's peso has depreciated 26 percent since the third quarter last year.
Pemex's crude oil production next year is expected to remain near current levels, at between 2.2 million and 2.3 million bpd in 2016.
Output has dropped a third since hitting peak production of 3.4 million bpd in 2004.
In one bright spot in the quarterly results, Pemex's tax bill dipped by half to 99.6 billion pesos ($5.9 billion).
The energy reform approved by Mexico's Congress last year ended the decades-long monopoly enjoyed by Pemex and opened the sector to private producers in hope of luring new investment. ($1 = 16.933 pesos at end-September) (Reporting by Gabriel Stargardter and David Alire Garcia; Editing by Simon Gardner, W Simon and David Gregorio)