(AFP) - Anti-narcotics agents working for the US government have laundered or smuggled millions of dollars in drug proceeds to see how the system works and use the information against Mexican drug cartels, The New York Times reported Sunday. Citing unnamed current and former federal law enforcement officials, the newspaper said the agents, primarily with the Drug Enforcement Administration, have handled shipments of hundreds of thousands of dollars in illegal cash across borders. Some 45,000 people have been killed in Mexico since 2006, when its government launched a major military crackdown against the powerful drug cartels that have terrorized border communities as they battled over lucrative smuggling routes. According to these officials, the operations were aimed at identifying how criminal organizations move their money, where they keep their assets and, most important, who their leaders are, the report said. The agents had deposited the proceeds in accounts designated by traffickers, or in shell accounts set up by agents, the paper noted. While the DEA conducted such operations in other countries, it began doing so in Mexico only in the past few years, The Times said. As it launders drug money, the agency often allows cartels to continue their operations over months or even years before making seizures or arrests, the report said. According to The Times, agency officials declined to publicly discuss details of their work, citing concerns about compromising their investigations. But Michael Vigil, a former senior official who is currently working for a private contracting company called Mission Essential Personnel, is quoted by the paper as saying: "We tried to make sure there was always close supervision of these operations so that we were accomplishing our objectives, and agents weren?t laundering money for the sake of laundering money."