Former Mexican defence minister Salvador Cienfuegos has been arrested in the United States on undisclosed charges, Mexico’s foreign minister said on Thursday.

Cienfuegos, who was defence chief from 2012-2018, was reportedly on a trip with his family when he was arrested at Los Angeles airport.

“The consul in Los Angeles will inform me of the charges in the next few hours. We will offer the consular assistance to which he is entitled,” Foreign Minister Marcelo Ebrard wrote on Twitter.

The Mexican investigative magazine Proceso, quoting unnamed sources at the US Department of Justice, reported that the arrest was the result of a long-standing investigation into corruption involving drug traffickers.

The Wall Street Journal newspaper, quoting an unnamed senior Mexican government official, said Cienfuegos was arrested at the request of the US Drug Enforcement Administration (DEA).

There was no immediate confirmation from the US authorities.

Cienfuegos, 72, headed the defence ministry under former President Enrique Pena Nieto.

As defence minister, Cienfuegos was a powerful figure in Mexico’s drug war in which the army battled cartels across the country. Several of Mexico’s former top-ranking “drug war” officials have been implicated in narcotics.

Under Cienfuegos, the Mexican army was accused of frequent human rights abuses, but that was true of his predecessors and his successor in the post.

The worst scandal in Cienfuegos’ tenure involved the 2014 army killings of suspects in a grain warehouse. In June 2014, soldiers killed 22 suspects at the warehouse in the town of Tlatlaya.

While some died in an initial shoot-out with the army patrol – in which one soldier was wounded – a human rights investigation later showed that at least eight and perhaps as many as a dozen suspects were executed after they surrendered.

More than 296,000 people have been murdered since the government militarised the fight against the drug cartels in 2006, according to the authorities, who say most of the killings are linked to gang violence.

Cienfuego previously complained about his troops having to take part in the country’s war on drug trafficking, saying the military was not suited for the job.

“We didn’t ask to be here. We don’t like it. We didn’t study how to chase criminals,” he said.

“Our function is something else and it’s been made into something unnatural. We are doing things that don’t correspond to our training because there’s no one else to do them,” the minister said.

Cienfuegos is the second former Mexican minister who is detained in the US.

Ex-public security minister Genaro Garcia Luna was arrested in Texas in December 2019 on charges of taking huge bribes to allow the notorious Sinaloa cartel to ship drugs into the US.