MADRID (AP) — A prominent former Mexican politician was detained Friday at Madrid's airport by anti-corruption officers and was being questioned by a judge, Spanish officials said.

Former Institutional Revolutionary Party chief Humberto Moreira was taken into custody based on a Spanish arrest warrant, said an official with the national police who spoke on condition of anonymity because of police policy. The official had no other details about why Moreira was sought by Spanish anti-corruption officers.

A court spokesman confirmed Friday night that Moreira was being questioned.

Moreira resigned in 2012 as party leader under a cloud of state government debt that accumulated under his governorship of Coahuila from 2005 to 2011. The debt was financed at least in part by falsified documents.

Moreira has not been charged in the U.S. or Mexico.

But two of Moreira's top associates have pleaded guilty in federal court in San Antonio, Texas, to conspiring to transport stolen money. In the plea agreement for businessman and media owner Roland Gonzalez Trevino dated last April, Moreira appears unnamed as co-conspirator 1, "a high-ranking official in Coahuila" who won the governorship. The plea agreement said he started in January or February of 2006 "taking money for his own personal use from the government of Coahuila."

Gonzalez admitted to participating in a plan to defraud or steal money from Coahuila with co-conspirator 1 and others. Gonzalez also admits to transferring more than $1.8 million that was "stolen, converted or taken by fraud" from the state of Coahuila and sent to the U.S.

Moreira's former state treasurer, Hector Javier Villarreal Hernandez, also pleaded guilty in 2014 in San Antonio to conspiracy to launder money and conspiring to transport stolen money.

Moreira left the governorship in 2011 to head the Institutional Revolutionary Party just as it was gearing up for a return to national power with candidate Enrique Pena Nieto, now the Mexican president. Moreira resigned when it was revealed that the Coahuila state debt rose from $27 million to nearly $3 billion during his tenure.

The party issued a statement Friday saying it had too little information to comment, adding, "Institutions are not responsible for the actions of individual members."

Associated Press writers Alex Oller in Barcelona, Spain, and Katherine Corcoran in Mexico City contributed to this report.