Naval personnel seized nearly 300,000 liters (79,256 gallons) of fuel aboard a tanker headed for Honduras, the Mexican Navy Secretariat said Monday.
The fuel was found during a routine inspection in Ciudad del Carmen, a city in the southeastern state of Campeche, by naval personnel, customs agents and employees of the Marinos del Carmen shipping agency.
The Mexican-flagged Isla del Carmen was carrying 291,971 liters (77,134 gallons) of diesel that were not listed in the Navigation Daily and the ship's officers admitted was obtained from other fuel ships, the secretariat said.
The crew, ship and fuel were turned over to federal prosecutors following the inspection, which occurred on May 15 but was not reported until Monday, the secretariat said.
Fuel theft has been rising over the past few years, increasing 38 percent in 2011, compared to the previous year, to 6.8 million barrels, state-owned oil giant Petroleos Mexicanos, or Pemex, said in a report submitted to Congress in May.
Last month, army troops found clandestine oil depots containing 1.5 million liters (396,258 gallons) of stolen fuel in the eastern state of Veracruz.
Soldiers from the 29th Military Zone found the clandestine fuel depots in Ejido Tacoteno, a community outside the city of Minatitlan.
The depots held 1.4 million liters of crude oil, 141,000 liters of diesel and 16,000 liters of export-grade UBA diesel, the secretariat said.
Two tanker trucks and eight tanks on trailers were seized at the site, which is near one of Mexico's six oil refineries.
Drug cartels and other transnational criminal organizations, or TCOs, are using fuel theft as a source of revenue.
Pemex is suing 14 companies in the United States for allegedly buying stolen fuel from the Los Zetas drug cartel. EFE