Mexico's Attorney General's Office has asked the country's top financial regulator to freeze bank accounts opened under the name of Tomas Yarrington, a former state governor accused of taking bribes from drug cartels, officials said.

The request was submitted to the National Banking and Securities Commission, or CNBV.

Yarrington's successor as governor of the northeastern state of Tamaulipas - Eugenio Hernandez, in office from 2004 to 2010 - also is under investigation in the same case, sources with the AG's office told Efe.

They said the legal action taken thus far in Mexico has targeted purported front men for Yarrington, including businessman Eduardo Rodriguez Berlanga, who has already given statements to federal prosecutors and whose legal status will be determined shortly.

Two other suspects, Napoleon Rodriguez de la Garza and Zonia Nereida De Pau Garcia, are being held in preventative detention while authorities continue to investigate them for money laundering.

The sources also said the Siedo organized crime unit of the AG's office has issued several arrest orders for individuals who allegedly made financial and real-estate transactions with illicitly acquired funds.

They added that the U.S. Justice Department has requested information from Mexico about Yarrington's net worth as part of its investigation into the former governor.

U.S. federal prosecutors on May 22 filed forfeiture cases involving two properties in Texas they say Yarrington purchased via front men using bribes from drug cartels.

Mexico's Institutional Revolutionary Party, or PRI, which is poised to retake the presidency this year after more than a decade in opposition, has suspended Yarrington's membership pending the results of the investigations.

Yarrington, who governed the border state of Tamaulipas from 1999-2004, "should face his individual responsibility before the courts," the PRI said in a statement last week.

The PRI's Enrique Peña Nieto, a photogenic former governor of the central state of Mexico, leads in the polls ahead of the July 1 presidential election.

The PRI governed Mexico without interruption from 1929-2000, a regime described by Nobel Prize-winning novelist Mario Vargas Llosa as "the perfect dictatorship."

Last October, President Felipe Calderon, of the conservative National Action Party, suggested in an interview with The New York Times that some PRI members would be susceptible to making deals with organized crime if the party regained power.

It is generally accepted that PRI administrations brokered agreements among rival drug cartels to prevent bloody turf battles of the kind that have become routine in Mexico over the last five years.

Peña Nieto's frontrunner status in the presidential race is due in part to Mexicans' frustration over persistently high levels of drug-related violence throughout Calderon's term.

Calderon militarized the struggle against Mexico's heavily armed, well-funded drug mobs shortly after taking office in December 2006, deploying tens of thousands of troops across the country.

The strategy has led to headline-grabbing captures of cartel kingpins, but drug violence has skyrocketed and claimed more than 50,000 lives. EFE