MEXICO CITY, Nov 14 (Reuters) - Mexico's national oil company Pemex's biggest refinery has begun bringing plants back online following a prolonged stoppage caused by a major earthquake in September, a company spokesperson said on Tuesday.

A partial start-up of the facility's plants began last week at the Salina Cruz refinery, located along the Pacific coast of southern Oaxaca state. But the facility has yet to begin production of any refined products, the official said, declining to be named in line with company policy.

When operational, Salina Cruz can process up to 330,000 barrels per day, the largest refining capacity of any of Pemex's six domestic refineries.

"Hopefully in the coming days we'll start production," the official said.

"But we don't want to give precise dates (for when output from the facility will begin) because it's been a very complex process due to the continuous aftershocks" following the September 7 earthquake, which damaged thousands of homes in Oaxaca and nearby Chiapas state, claiming 102 lives.

Pemex, officially known as Petroleos Mexicanos, has previously said that the quake caused electrical problems at the plants but no structural damage.

Last month, new electric turbogenerators were installed at the refinery to begin tests needed to bring the facility back online.

In June, Salina Cruz had been shut down due to a fire caused by flooding from a major storm and began operating briefly at the end of July. (Reporting by Ana Isabel Martinez; Writing by David Alire Garcia; editing by Diane Craft)