Updated

Mexican court authorities have suspended two federal judges who presided over high-profile drug cases, saying investigators are looking into possible irregularities involving the jurists.

The Federal Judiciary Council said Friday evening that it was temporarily relieving appellate Judge Jesus Guadalupe Luna and district Judge Efrain Cazares of their duties, but its statement didn't describe the allegations being investigated. The Attorney General's Office declined to comment Saturday.

Both judges have taken part in cases involving well-known people with alleged ties to Mexico's drug business.

In April 2008, Luna ordered the release of the son of purported Sinaloa drug cartel chief Joaquin "El Chapo" Guzman. Ivan Archivaldo Guzman Salazar had been sentenced by a lower court to five years in prison for money laundering, but the appellate judge ruled that there was no proof the money he used to open two bank accounts came from drug trafficking and that being the son of the infamous capo wasn't grounds for imprisonment.

Last summer, Luna upheld a lower court ruling that cleared Sandra Avila Beltran of organized-crime charges despite efforts by Mexico and the U.S. to prosecute the woman nicknamed "Queen of the Pacific." Avila is wanted on a 2004 U.S. indictment as a suspect tied to the seizure of more than nine tons of U.S.-bound cocaine on Mexico's west coast.

A judge acquitted Avila in December 2010 of charges stemming from that drug confiscation, and Luna backed that decision by citing a lack of evidence.

U.S. authorities have sought extradition of Avila, a niece of Miguel Angel Felix Gallardo, known as "the godfather" of Mexican drug smuggling, but that has been rejected twice by other judges on grounds she shouldn't be prosecuted in the U.S. on charges that have been dismissed in Mexico.

The other suspended judge, Cazares, has been accused by Mexico's government of ignoring credible evidence when he released some of the mayors detained in a mass arrest of officials in the western state of Michoacan in 2009. The federal attorney general alleged the officials had ties to the La Familia drug gang, and prosecutors filed a complaint against Cazares saying he improperly acquitted the officials.

With all of the officials freed by various judges, the crackdown became one of the most embarrassing episodes in President Felipe Calderon's 5 1/2-year-long offensive against drug cartels.

Most recently, drug battles have escalated as Mexico's two most powerful drug cartels, the Sinaloa and Zetas gangs, wage a war in several regions considered strongholds of one or the other.

Late Friday, a group of armed men opened fire on a police station in the border city of Matamoros, which is across the Rio Grande from Brownsville, Texas. Tamaulipas state Interior Secretary Morelos Canseco Gomez said they threw an explosive, possibly a grenade, but no one was injured in the attack. Canseco said he did not know the motive or the gang behind it.

The attack came only days after suspected drug cartel gunmen set off a car bomb near a police barracks in the same state, wounding eight officers.

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Adriana Gomez Licon on Twitter: http://twitter.com/agomezlicon