MEXICO CITY – Mexico's state-run oil company says output fell 9 percent to 2.83 million barrels a day in the first eight months of the year.

Petroleos Mexicanos says sagging oil production is due a drop at its main Cantarell oil field. Output there was down by 26 percent to 998,000 barrels a day.

The company said Monday that the decline helped cut exports to 1.43 million barrels a day, down 16 percent from the year-ago period.

An energy reform bill proposed by President Felipe Calderón last month aims to boost flagging production by opening the sector to more private and foreign investors.

Oil income makes up about 40 percent of Mexico's annual budget.