Mexico City ? Mexico’s government on Monday offered up to $2 million each for information leading to the arrest of 24 top drug lords in a public challenge to the cartels’ violent grip on the country.

The list indicated that drug gangs have splintered into six main cartels under pressure from the U.S. and Mexican governments. The two most powerful gangs — the Pacific and Gulf cartels — each suffered fractures that have given rise to new cartels, according to the list published by the Attorney General’s Office.

The list offers rewards of up to $2 million for 24 top members of the cartels and $1 million for 13 of their lieutenants.

Mexico’s drug violence has killed more than 9,000 people since President Felipe Calderon took office in December 2006 as gangs battle each other for territory and fight off a government crackdown. Some of that violence is spilling over into the United States, especially the Southwest, where kidnaps and killings are on the rise.

The rewards are the largest Mexico has ever offered for top drug lords, said Ricardo Najera, a spokesman for the Attorney General’s office. Some of the men, such as suspected Pacific cartel leaders Joaquin Guzman and Ismael Zambada, are targeted by separate $5 million reward offers from the U.S. government.

The new list appeared to be the first offering rewards for all the most-wanted cartel members at once. The government could be trying to signal its determination to take on the cartels at the same time, rather than one or two at a time as past administrations have done, said Andrew Selee, director of the Wilson Center’s Mexico Institute.