Nuevo Leon Governor Rodrigo Medina urged Calderon to send more troops to Monterrey and surrounding areas, echoing a plea published on Wednesday from Mexican business groups in a full-page statement in local newspapers.

Security forces found the body of a slain mayor on Wednesday near Mexico's richest city, days after he was abducted by hitmen in the latest attack on a public official from increasingly bold drug cartels.

Medina said this week that Cavazos, who took office last year, was probably targeted for his efforts to clean up Santiago's corrupt police force, part of a nationwide effort to curb endemic police graft. The mayor of the San Pedro Garza Garcia municipality, part of Monterrey, said drug gangs threatened Cavazos directly late last year. 

"When the mayor took office, he told me that criminal groups had gone to see him, saying: either you join us or we eliminate you," Mayor Mauricio Fernandez told local radio.

Santiago, a popular weekend getaway for Monterrey residents, has also become a staging post for drug gangs smuggling narcotics north into the United States. Many capos have taken refuge in mansions nestled in surrounding hills.

More than 28,000 people, mainly drug traffickers and police, have been killed in Mexico's drug war since December 2006, intensifying worries in Washington about the stability of the United States' oil-producing neighbor.

Interior Minister Francisco Blake was due in Monterrey later in the day to discuss the killing with local leaders.