The Mexican army seized a shoulder-fired missile, a rocket launcher and three grenades in an operation against drug trafficking in the Gulf of Mexico state of Veracruz, the Defence Department said Tuesday.

Soldiers also found four rifles, 2,870 rounds of ammunition, a bulletproof vehicle, and packages of cocaine and marijuana in a raid in the ranch town of El Guayabal.

Unidentified men fled the ranch when the troops arrived Monday and couldn't be captured.

The Zetas drug cartel controls drug trafficking in the state of Veracruz but has been locked in a fight with a gang aligned with the Sinaloa cartel since last year.

The discovery of rocket launchers and missiles remains rare in Mexico's 5-year-old drug war, but the government says some drug cartels have added such weaponry to their arsenals.

Also Tuesday, the U.S. Treasury Department announced that it is imposing sanctions on the brother of Ismael "El Mayo" Zambada, who leads the Sinaloa Cartel along with Mexico's most-wanted fugitive, Joaquin "El Chapo" Guzman.

The department designated Jesus Reynaldo Zambada Garcia, 50, as foreign drug trafficker under the Kingpin Act, prohibiting people in the U.S. from conducting businesses with him and freezing his U.S. assets. A statement said Jesus Zambada ran a drug trafficking route via Mexico City's airport on behalf of his brother.

Jesus Zambada was arrested in October 2008 and his extradition to the U.S. is pending.