By Andres R. Martinez and Jens Erik Gould

Feb. 27 (Bloomberg) -- Mexico’s National Banking and Securities commission said it’s studying the legal impact of the U.S. government’s stake in Citigroup Inc., which owns Grupo Financiero Banamex SA.

The U.S. government announced today it plans to convert as much as $25 billion of preferred shares of Citigroup into common stock. The conversion would give the U.S. a 36 percent stake in the New York-based company. Mexico’s banking law prohibits foreign governments from owning or having a stake in banks that operate in Mexico, like Banamex. Citigroup purchased Banamex for $12.5 billion in 2001.

The commission has asked all banks operating in Mexico that have received help from governments to provide information on the aid, the statement said. The banking commission and other financial authorities will “soonâ€