Updated

The United States Thursday offered a reward of up to $5 million for information leading to the capture of a reputed Mexican drug cartel chieftain, whose group allegedly smuggles tons of cocaine and marijuana north each year.

Jorge Eduardo Costilla Sanchez has been charged in the U.S. with 12 counts of drug trafficking and money laundering and is also wanted for assaulting a federal law enforcement officer, U.S. Ambassador Tony Garza said in a U.S. Embassy statement.

"In addition to being an extremely dangerous criminal, Jorge Eduardo Costilla Sanchez is the linchpin of a network of drug dealers and murderers," he said.

He said Costilla Sanchez is believed to be the leader of the Gulf Cartel, an organization responsible for the distribution of thousands of pounds of cocaine and marijuana into Mexico and the United States yearly.

"Residents of our border communities will be significantly safer if he is apprehended and bought to justice," Garza said.

Costilla Sanchez has been linked to the brutal killing of newspaper columnist Francisco Arratia Saldierna, who was beaten to death in Matamoros in August 2004. Arratia Saldierna's reports on drug trafficking and organized crime might have prompted the attack.

The Gulf Cartel was thought to be headed by Osiel Cardenas until his 2003 capture following a shootout with police in Matamoros.

Mexican authorities believe Cardenas has continued to run much of his drug gang's operations from prison and may have formed an alliance with another jailed kingpin, Benjamin Arellano Felix, who is accused of heading the Tijuana-based smuggling syndicate that bears his family's name.

Both men are being held in the top-security La Palma prison west of Mexico City.

But Thursday's announcement emphasized Costilla Sanchez's role as chief of the cartel.

"We offer a reward of up to $5 million for information leading to his arrest," Garza said.

U.S. officials say that while Colombia remains the world's biggest producer of cocaine, more than 90 percent of it enters the United States through Mexico, and cartels based in this country are now the most powerful in the world.

Investigators have blamed mounting violence along the U.S.-Mexico border on a turf war between rival cartels over billion-dollar smuggling routes into the United States.