MADRID (Reuters) - Spanish police arrested a former ally of Mexican President Enrique Pena Nieto on Friday in a money-laundering probe, potentially raising awkward questions for his ruling Institutional Revolutionary Party (PRI).
Humberto Moreira, who was PRI chairman in 2011 before he stood down after a debt scandal was uncovered in Coahuila, the northern state he had previously governed, was arrested at Madrid's international airport, Spanish police said.
His detention was part of an operation against money laundering and other crimes, according to a Spanish court official who spoke on condition of anonymity.
In an apparent reference to Pena Nieto's Tweet to announce the capture of drug lord Joaquin "El Chapo" Guzman a week ago, Spanish police tweeted news of Moreira's detention with the hashtag "mission accomplished", echoing the president's words.
Details of the Spanish probe were not immediately available, but it raised hopes among opposition politicians that Moreira might face prosecution over the debt debacle.
"Nobody in the Coahuila government has explained what happened to that money," said Senator Ernesto Cordero of the opposition National Action Party (PAN), an ex-finance minister who led initial investigations into the debt.
Moreira is not wanted by the law in Mexico, and a presidency spokesman said he had no information on the arrest.
In 2014, Moreira's former finance secretary in Coahuila pled guilty to federal money laundering charges in Texas, and the man who completed his term as governor is also wanted in the United States on suspicion of embezzling millions.
Moreira was in office from 2005 to early 2011, a period in which Coahuila's debts more than tripled to a sum then worth around $3 billion. Some of the loans were contracted by the state congress with falsified documents, Cordero said.
Moreira maintained he had been misled by officials and denied any wrongdoing.
Guillermo Anaya, a senior PAN politician in Coahuila, said there was concern that the loans could have ended up helping the PRI to fund state and even national election campaigns.
Elected president in July 2012, Pena Nieto's campaign to be the PRI candidate gained momentum under Moreira.
Pena Nieto has faced criticism for failing to go after PRI officials accused of graft, including three of its former governors indicted in the United States.
The PRI said it had "little information" on the matter, but added: "The institutions are not responsible for the acts of those who form part of them."
(Reporting by Dave Graham and Lizbeth Diaz in Mexico City and Rodrigo de Miguel in Madrid; editing by Chris Reese and Alistair Bell)
