Oct. 28 (Bloomberg) -- U.S. authorities are investigating reports that a worker at the U.S. Embassy in Mexico City passed information to a drug cartel, State Department spokesman Robert Wood said.

``There's an ongoing investigation right now,'' Wood told reporters in Washington today. The U.S. Drug Enforcement Administration ``will certainly play a role'' in the probe, he said.

Wood said he couldn't comment further because the matter is under investigation. Mexico's attorney general's office says it has no information about any infiltration of the U.S. Embassy. There are no plans to investigate, as the matter is outside the Attorney General's purview, the press office said in an e-mail.

The U.S. has agreed to provide $400 million in aid this year to help Mexico tame violence related to organized crime and drug trafficking, which has resulted in more than 4,000 killings this year in Mexico. Mexican cartels have grown rich by selling $13.8 billion a year worth of marijuana, cocaine, heroin and amphetamines to the U.S., according to White House figures.

Liz Detter, deputy spokeswoman for the U.S. embassy in Mexico, declined to comment on the allegations, which were reported yesterday in Mexican newspaper El Universal.

Mexican Attorney General Eduardo Medina Mora said yesterday that employees at his office passed confidential information to narcotics traffickers in the worst case of infiltration of law enforcement by drug cartels in 10 years.

$450,000 Payments

Thirty-five employees of Mexico's organized-crime unit were each paid as much as $450,000 a month by the Sinaloa drug cartel for the information, Medina Mora said. Some employees had been passing on sensitive information since 2004. The technical director of the organized-crime unit has been arrested and is awaiting extradition to the U.S. for allegedly conspiring to sell cocaine in that country.

``We must follow more lines of investigation of people who, it seems, also obtained classified information,'' Medina Mora said. The investigation began with a statement by an anonymous person in Mexico's embassy in the U.S.

``To confront crime, we first have to remove it from our own house,'' President Felipe Calderon said today during a speech in Mexico City. ``That is precisely what we are doing.''

To contact the reporter on this story: Viola Gienger in Washington at vgienger@bloomberg.net; Jens Erik Gould in Mexico City at jgould9@bloomberg.net

Last Updated: October 28, 2008 16:17 EDT