Agents found $52,167 in the Mexican singer's carryon luggage during a random search of passengers waiting to board a flight to Los Angeles, the Attorney General's Office said in a statement. Rivera had previously told authorities she was carrying $20,000.
Rivera was being questioned late Monday and authorities were determining whether she would face charges, the agency said.
The singer's publicist, Arturo Rivera, declined to comment, saying he was not yet familiar with the circumstances surrounding her detention.
Rivera, who lives in California, participated in a television show in Mexico City on Sunday night.
The singer, whose hits include "Guilty or Innocent," won female artist of the year in the Mexico regional category of the 2009 "Premios Lo Nuestro" awards.
Rivera has had trouble with the law before, including allegations of assault. She has also filed a legal complaint against an unidentified person over the publication of a sex tape.
In 2007, her ex-husband was convicted of sexually molesting his daughter and sister-in-law.
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