Son of ex-Mexican opposition party chief shot dead

Jose Eduardo Moreira (R front row), the son of the former chairman of Mexico's Institutional Revolutionary Party (PRI) and ex-Coahuila state governor Humberto Moreira, poses for a photograph with others in Acuna August 28, 2012.

MEXICO CITY (Reuters) - The son of the embattled former leader of the Mexican political party set to take power in December was found shot to death in a town south of the U.S. border notorious for drug cartel violence, authorities said on Thursday.

Jose Eduardo Moreira, 28, the son of the former chairman of Mexico's Institutional Revolutionary Party, or PRI, and ex-Coahuila state governor Humberto Moreira, was found shot to death near Ciudad Acuna, across the Rio Grande river from Texas, late on Wednesday, the state's public safety director said.

The son worked in the frontier town for the state government now led by his uncle, Ruben Moreira, had been reported missing several hours earlier.

Ciudad Acuna is a key transit point for powerful cartels hauling drugs to Texas. It was not immediately clear if Moreira's murder was linked to organized crime in the city.

President-elect Enrique Pena Nieto, who will be sworn in on December 1 as president for the PRI, called the killing an "irreparable loss" to the Moreira family in a Tweet, and said the "murder should not go unpunished."

Humberto Moreira stepped down as the PRI's chairman late last year, under pressure from a financial scandal stemming from his time as governor of Coahuila from 2005 to 2011. He has since kept a low public profile.

The killing was also condemned by outgoing President Felipe Calderon, who offered his condolences, saying that he "deeply regretted this cowardly murder."

(Reporting by Lizbeth Diaz, Miguel Angel Gutierrez and Verónica Gomez Sparrowe; Writing by Tim Gaynor; Editing by Doina Chiacu)