Denise Saad, who commutes from the outskirts, was happy happy recently to receive a government-issued card to replace the outdated coin-operated system on the buses.

“It’s great the bus system is finally being updated,” she said.

But the 31-year-old theater producer was surprised to learn that her movements were being tracked through the new card, known as SUBE.

It’s one of several new measures that enhance the government’s surveillance and control capacity that have civil liberties groups raising red flags — and Argentines like Saad raising eyebrows.

Another initiative, decreed by President Cristina Fernández de Kirchner late last year, ordered the creation of the Federal System of Biometric Identification. In a sprawling, centralized system, biometric data — such as fingerprints and facial scans — will be integrated between the National Registry of Persons and the Argentine Federal Police. Starting Jan. 1, even newborns began having their biometric information registered in the system.

And as national documents and passports expire and are renewed, the unique physical characteristics of all 40 million Argentines will eventually be recorded in a government database, available to federal and provincial authorities...