The hearing in Dolores, some 200 kilometers (124 miles) south of Buenos Aires, was postponed within minutes after Macri's lawyer argued the court "does not have the authority" to lift secrecy provisions on state intelligence for him to testify.

But late Thursday, current President Alberto Fernandez signed a decree shortly before leaving for the G20 summit in Rome that lifted those secrecy provisions, allowing his testimony, officials said.

The ARA San Juan sub disappeared in November 2017. When it was found just over a year later, it was at a depth of more than 900 meters (2,950 feet) in a desolate area of the South Atlantic some 400 kilometers off the coast of Argentina.

It had been crushed from an implosion apparently caused by a technical fault. Authorities decided against attempting to refloat it.

Family members of the 44 crew members told investigators they were followed and wiretapped, filmed and intimidated into abandoning any claims related to the incident.

Macri, 62, is accused of ordering the espionage. He risks between three and 10 years in jail for allegedly violating Argentina's intelligence laws.

No new hearing date has been set.

Macri led the country from 2015 to 2019 and is now the leader of Argentina's right-wing opposition.

According to his lawyer, Pablo Lanusse, the timing of Thursday's hearing ahead of legislative elections next month suggested "animosity" on the part of the presiding judge.

Macri addressed more than 100 supporters who had gathered outside the court to greet him, and accused the authorities of "using a tragedy" for political purposes during a campaign for November 14 elections for half the seats in the Chamber of Deputies and a third of the Senate.

"We hope that Macri... will tell us the truth about why we were illegally spied on," Luis Tagliapietra, father of one of the submariners, told AFP.

Macri has denied ordering surveillance of the families.

Judge Martin Bava has ordered the prosecution of secret service heads Gustavo Arribas and Silvia Majdalani, who reported to Macri at the time.

In March, two former Argentine military chiefs were sanctioned over the sinking.

Retired admiral Marcelo Srur was handed "45 days of arrest" for having given the defense ministry an "incomplete" picture of what happened.

Claudio Villamide, the former commander of the Submarine Force, was dismissed after he was found guilty of a "lack of care and neglect of the troops and equipment under his charge."

Two active captains were given detentions of 20 and 30 days and the former head of a naval base in the south of the country was detained for 15 days.