That deployment kicked off a new war on drug-related violence which killed an estimated 2,000 people in 2006.

"We are determined to regain security, not just in Michoacan or Baja California, but in every part of Mexico that is threatened by organised crime," Calderon said on Wednesday, visiting troops in Michoacan, in western Mexico.

Calderon took office on December 1.

Murder every day

Tijuana, just south of San Diego and one of the busiest border crossings into the US, sees a murder almost every day and two kidnappings a week, most blamed on brutal rivalries between drug cartels.

The city's drug trade is dominated by the Arellano Felix cartel, which battles rival gangs from the northwestern state of Sinaloa.

Eduardo Medina Mora, attorney-general, said there was evidence criminal gangs had infiltrated the local police.

"This is about getting Tijuana out of the hands of criminal organisations," he said.

Cocaine flow

Huge quantities of South American cocaine pass through Mexico on its way to the US, and Mexico also produces marijuana, methamphetamines and heroin.

Mexico's municipal police are so poorly paid and badly equipped that even officers not in the pay of crime gangs are widely considered inept.

Calderon's predecessor, Vicente Fox, declared war on drug gangs in early 2005, but the crackdown only intensified turf wars between cartels.

Gang-related murders and drive-by shootings spread down Mexico's Pacific coast.