A compressor in a desulphurisation unit at Petroleos Mexicanos (Pemex) 235,000 barrel-a-day Cadereyta refinery in Monterrey exploded killing one person and injuring 10 on 7 September.
The refinery is still operating but it is the second such incident to hit Latin Americas largest oil producer in the past six weeks.
The person who died and seven of the injured workers are Pemex employees, the company says. The other three people hurt were contractors from Carso Infraestructura y Construccion.
Pemex officials are analysing the effects of the accident at the site. The company shut its coker after the explosion and the explosion did not damage the refinerys processing plants.
The accident follows an explosion at a coking unit petrol storage tank at the companys Francisco I Madero refinery on the Gulf of Mexico on 29 July.
Mexico is a net importer of refined petroleum products. In 2009, Mexico imported 519,000 barrels a day of refined petroleum products, while exporting 244,000 barrels daily. Petrol represented about 60% of its product imports.
Pemex is building its first refinery in three decades in the state of Hidalgo to keep up with rising gasoline demand as more Mexicans buy cars.
Mexicos six refineries were able to process 1.35 million barrels a day in 2009, according to Energy Ministry figures. The plants ran at about 70% capacity last year.