The Mexican attorney general's office said on Sunday it is investigating the purchase of Pegasus computer spyware by the previous administration and whether it was carried out legally.
In a statement, the office referred to existing probes of two people, including a prominent ex-official, into the use of Pegasus spyware, days after the current government denied it had spied on journalists or critics.
Pegasus belongs to Israeli spyware firm NSO Group, which typically only sells the software to governments or law enforcement organizations.
In the statement, Mexican prosecutors said they were looking at the acquisition of Pegasus by the prior attorney general's office for 457 million pesos ($23 million). They were trying to establish if it had been done with the proper justification, and had followed requisite public tender procedures.
In the second probe, the office said that judicial authorities had received evidence that NSO had been "illegally selling" Pegasus, without providing more details.
NSO did not immediately reply to a request for comment.
Licensing Pegasus only to law enforcement
Earlier this month, NSO told Reuters it licenses Pegasus only to law enforcement and intelligence agencies of sovereign states and government agencies following Israeli government approval, and terminates contracts when wrongdoing is detected.
NSO noted it does not operate Pegasus, has no visibility on its usage, and does not collect information about customers.
The attorney general's announcement was issued nearly two weeks after President Andres Manuel Lopez Obrador denied his officials spied on journalists or opponents after a watchdog's report that the phones of at least three people investigating human rights abuses in Mexico were infected with Pegasus.
Lopez Obrador won office in 2018 having pledged during his election campaign to put an end to the government spying on its citizens.