The attorney general's office of Mexico state, adjoining Mexico City, said the suspect, Oscar Osvaldo Garcia Montoya, was detained early Thursday.

He allegedly admitted to personally taking part in 300 killings and ordering another 600 by members of his organization, Alfredo Castillo, attorney general of Mexico state, told a news conference.

Garcia Montoya, who led a group nicknamed "The Hand with Eyes," was a former soldier and had trained with the Kaibiles special operations force of Guatemala's army, authorities said.

He allegedly had links with gangs including the Beltran Leyva cartel and that of drug kingpin Edgar Valdez Villarreal, known as "La Barbie," who was detained in August 2010.

Mexican poet Efrain Bartolome and his wife Guadalupe Belmontes, a writer, complained Thursday that their house was targeted in the violent raid that netted Garcia Montoya.

"They threatened us, they threw us to the ground, they gave a slap in the head to my husband and shouted 'Where are the weapons?' before leaving, with no explanation," Belmontes told AFP.

Castillo later apologized to the family and admitted that "some errors" had been made during the operation.

Complaints of violations of homes by security forces in operations under President Felipe Calderon's drug war have recently multiplied in Mexico, according to the National Commission on Human Rights.

Calderon launched a military crackdown on drug gangs after taking office in December 2006. Drug-related violence is blamed for more than 41,000 deaths in Mexico since then.