MEXICO CITY — Mexico’s government has issued an arrest warrant for the former director of the country’s state-run oil company, the state news agency reported Tuesday. The arrest of former Pemex director Emilio Lozoya on corruption charges would be the boldest yet by President Andrés Manuel López Obrador — and one likely to antagonize Mexico’s political elite.

The warrant comes a day after Mexico’s government announced it was freezing Lozoya’s bank account and the bank account of one of Mexico’s largest steel companies, Altos Hornos de Mexico, or AHMSA. The government said in a statement that the accounts included funds “presumed to be derived from acts of corruption.” 

López Obrador won the presidential election last year on an anti-corruption platform that resonated with voters tired of predecessor Enrique Peña Nieto’s scandal-ridden administration. López Obrador spoke frequently of the “mafias of power” who he said had long ruled the country, and promised a zero-tolerance approach against graft.

But in the first months of his presidency, some supporters expressed disappointment that the new administration hadn’t made more progress. 

Lozoya’s arrest would be significant. Pemex is the second largest enterprise in Latin America, after the Brazilian oil giant Petrobras, and Lozoya was a prominent member of Peña Nieto’s inner circle.

Lozoya’s attorney said Tuesday “we will defend ourselves.”

“We have never hidden,” attorney Javier Coello Trejo told radio host Ciro Gómez Leyva before news of the warrant was published. “If they do things that are incorrect and have no legal basis, then we will defend ourselves with the law in hand.”

The state news agency report did not provide details of the warrant. The attorney general’s office declined to comment.

The country’s finance ministry said Monday that freezing Lozoya’s account “reaffirmed that the policy of zero tolerance for corruption is one of the central axes of the government of Mexico.”

The president’s financial crimes chief, Santiago Nieto, told the Wall Street Journal on Monday that the government had frozen Lozoya’s account over the $475 million sale of a fertilizer plant in 2014 from AHMSA to Pemex while Lozoya was director. Nieto said government investigators allege that bribes were paid as a part of that purchase. 

Alonso Ancira, the head of AHMSA, was detained by Interpol in Spain on Tuesday, according to several news reports. Mexico’s attorney general’s office declined to comment on Ancira’s case. 

AHMSA on Monday called the freezing of its account “unprecedented, arbitrary” and said it “violated [its] rights.”

“It was a total surprise,” AHMSA spokesman Francisco Ocuna told Bloomberg on Tuesday. “It’s absolutely illegal, the [financial intelligence unit] is acting as prosecutor and judge, without any due process.”

If Lozoya and Ancira were arrested, the next major challenge for López Obrador would be using Mexico’s notoriously weak judiciary to secure convictions.

According the Universidad de Las Americas Puebla, which conducts an annual study of crime reporting and conviction rates, Mexico consistently has the highest level of impunity in Latin America.