Updated

MEXICO CITY -- Mexico's state-owned oil company announced Wednesday it has filed a lawsuit against nine U.S. companies and two individuals for alleged involvement in buying or processing Mexican oil products stolen by gangs.

Petroleos Mexicanos said the lawsuit was filed last week in U.S. District Court in Houston, Texas.

Pemex said the suit is intended to "combat the theft and smuggling of gas condensate from its facilities in northern Mexico," including tanker trucks hijacked at gunpoint in northern Mexico. The thefts involved dozens of tanker-truck loads.

The suit does not claim any of the U.S. firms participated in the actual robberies, but says some knowingly conspired to ship the stolen goods, while others unwittingly handled them.

"All of the defendants have participated and profited, knowingly or unwittingly, in the trafficking of stolen condensate in the United States," the suit says, referring to a mix of oil liquids produced as a byproduct of natural gas wells.

"Some of the defendants knew, or at least should have known, they were trading in, or transporting, stolen condensate," the suit says. "Others were ignorant that they were purchasing stolen goods. In either case, however, the defendants took possession of Mexico's sovereign property without right or title. All defendants are therefore liable for their individual usurpation of Mexico's patrimony."

The lawsuit does not name a specific amount of damages being sought, but argues that the sued companies are liable for part or all of the $300 million in oil stolen since 2006.

Pemex has "lost large amounts of its condensate, at times approaching 40 percent of the production of condensate from the Burgos Field," the suit says.

A joint U.S.-Mexico investigation in 2010 found that smuggled oil stolen from Pemex was being transported across the border and sold to U.S. refineries. The Mexican government has said drug cartel members and other criminals are responsible for many of the oil thefts.

The gangs tap remote pipelines, and sometimes build pipelines of their own, siphoning off hundreds of millions of dollars worth of oil each year.

The suit says Mexico has filed criminal charges against about 140 people in Mexico for alleged involvement in the thefts, "including two Mexican customs agents who were jailed for allowing tanker trucks of stolen condensate to pass through Mexican customs and into the United States."

It said all the stolen oil ends up in the United States, "and particularly in Texas and neighboring states," since Pemex owns all the refineries and wells in Mexico and doesn't buy raw oil products from anyone else.

Two Texas oil company executives were convicted in 2010 of selling stolen Mexican oil products. They are not included in the suit.

Sis of the companies sued are based in Texas: Big Star Gathering LTD, F&M Transportation Inc., Western Refining Company LP, Joplin Energy LLC, Superior Crude Gathering Inc. and Plains All-American. The other three companies are TransMontaigne Partners LP of Denver, Colorado, SemCrude LP of Oklahoma City, Oklahoma, and Saint James Oil Inc. of Sandy, Utah.

Two U.S. oil company executives, James Jensen of Sandy, Utah, and Jeff Kirby of Corpus Christi, Texas, are also named in the suit.

None of the companies or individuals named in the suit returned calls for comment Wednesday.

Pemex charges that three of the companies -- Big Star, Superior Crude and F&M -- "actively and knowingly participated in a conspiracy to import and market the stolen condensate in the United States."

Others like TransMontaigne were negligent in not verifying the origin of shipments, while SemCrude, Plains and Western Refining "appear to have been entirely innocent and dealt in the condensate only after it was laundered," the suit says.

Still, the suit cites more than $10 million in SemCrude transactions involving such oil and said the company "is liable for all of its transactions involving the stolen property of Mexico."