An armed group stole the body of the slain leader of Mexico's brutal Zetas drug cartel from a funeral home in northern Mexico hours after he was killed in a gun battle with Marines.

Mexican Marines say initial forensic tests confirmed they had killed Zetas boss Heriberto Lazcano, one of Mexico's most wanted men.

Lazcano, also known as The Executioner, is the most powerful drug kingpin to fall in President Felipe Calderon's military offensive against the gangs. He was killed along with another suspected Zeta member in Sunday's clash.

The Zetas, considered one of the most powerful drug gangs in Mexico, have carried out some of the most violent acts in the country's drug war.