A Mexican army officer assigned to guard President Felipe Calderon leaked military intelligence to drug cartels, trained hit men and supplied military weapons to Los Zetas, according to a U.S. Embassy cable recently released by Wikileaks.

The U.S. Embassy cable, dated Jan. 20, 2009, says the case was the most serious security breach during the Calderon presidency and indicates that Mexico's powerful drug cartels have infiltrated large parts of the security apparatus.

One of the main reasons that the Mexican government relies on the army to fight the cartels is because the military is thought to be less corrupt than state and local police forces.

The document says Mexican officials had "sought to downplay the seriousness of the breach."

Calderon lashed out at senior American diplomats Tuesday, saying their "ignorance has translated into a distortion of what is happening in Mexico." He accused U.S. agencies of not doing enough to help Mexico combat the drug cartels.

"The institutional cooperation ends up being notoriously insufficient," Calderon told El Universal.

The comments were Calderon's first public criticism of the U.S. in response to a recent Wikileaks cable dump that highlights U.S. concerns over the depth of Mexico's drug-related problems.

His remarks came as mourners gathered for the funeral of a U.S. Immigration and Customs Enforcement agent who was shot and killed by Los Zetas hitmen in Mexico last week. The incident threatens to further strain cross-border relations.