A giant undercover operation exposed Mexican bankers laundering millions of dollars for Colombian and Mexican drug cartels, say U.S. officials who expect to arrest more than 180 people.

Federal officials on Monday announced the end of a three-year investigation of Mexican banks and bank officials - the first to link them directly to money laundering for the Cali cartel of Colombia and the Juarez cartel of Mexico."Today, we have hurt the drug cartels where it hurts most - in their pocketbooks," said Treasury Secretary Robert Rubin, who was joined by Attorney General Janet Reno for the announcement.

It was described as the largest drug-money laundering case in the history of American law enforcement.

More than 130 people already have been arrested and more than $35 million seized, officials said. Also, 2 tons of cocaine and 4 tons of marijuana were seized.

Officials were seeking to confiscate an additional $122 million sitting in U.S. and foreign bank accounts.

Reno said she and Rubin each informed their Mexican counterparts of the investigation on Monday and that both had "indicated a desire to cooperate."

Mexico's Attorney General's Office said it received news of the U.S. arrests "with satisfaction" and that some of those arrested were already under investigation in Mexico.

The Mexican Bankers Association, which represents most of the country's banks, issued a statement saying it had "unanimously decided to cooperate with the U.S. authorities."

"The Mexican Bankers Association supports in an unconditional form all of the measures taken to punish those guilty," said Carlos Gomez y Gomez, the association's president.

He said that those involved acted "in an individual form, and we are not dealing with an institutional practice of Mexican banks."

Indictments unsealed Monday in federal court in Los Angeles alleged that officials from 12 of Mexico's 19 largest banking institutions were involved in money laundering.

One indictment names 26 Mexican bank officials and three Mexican banks: Confia, Bancomer and Banca Serfin. Both Bancomer and Banca Serfin have branches in the United States.