Argentine police arrested on Sunday a companion of the man who attempted to shoot Vice President Cristina Kirchner after the politician's lawyers said the assailant "didn't act alone," local media reported.

Scandal-tainted Kirchner, 69, survived the assassination attempt as she mingled with supporters outside her home on Thursday night, when a gun brandished by Fernando Andre Sabag Montiel failed to fire.

Video footage showed Brenda Uliarte, 23, in the company of attacker Sabag Montiel on the day of the attack, local media said, citing sources close to the investigation.

Kirchner enjoys a loyal support base among followers of the center-left Peronism movement inherited from former president Juan Peron, but is disliked in equal measure by the political opposition.

Tens of thousands of Argentines took to the streets to denounce political violence after the shooting attempt.

Uliarte was arrested under a warrant issued by the magistrate in charge of the investigation, according to judicial sources cited by local media, including the official Telam news agency.

She had said in an interview with local television channel Telefe that she had been living with Sabag Montiel for more than a month but had not seen him in the 48 hours before the incident.

She also expressed shock that her friend had attempted to kill the vice president.

"To tell the truth, I don't remember any mention of the vice president. He was complaining about the dollar and the economy, like everyone else," she told Telefe.

Sabag Montiel, 35, a Brazilian national who has been living in Argentina since his youth, has not told investigators what his motivations were.

"He didn't act alone because there were preparatory actions to the assassination attempt," Kirchner's lawyer Gregorio Dalbon told C5N television station, without offering further details.

"There were, without a doubt, other people who were aware of this situation."

Kirchner, who is currently on trial for corruption and accused of accepting bribes in her Patagonian stronghold, was greeting supporters outside her Buenos Aires home when Sabag Montiel pointed a gun at her head from within the crowd.

For reasons as yet unknown, the weapon did not go off despite being fired, President Alberto Fernandez said shortly after the incident, which led to messages of support from the Pope, the UN, United States and Latin American leaders.

The attacker was arrested on the spot and the entire incident caught on camera.

Kirchner's lawyer has said he would also like investigators to interview a man named "Mario", who has identified himself as the attacker's friend.

Shortly after the attack, Mario had told a television channel that he had been friends with Sabag Montiel since they were teenagers and that he was "sure that his intention was to kill" Kirchner.

He also said he had not seen Sabag Montiel in 10 months, the period in which the would-be killer had sought to acquire a gun.

In photos on his Instagram account, he appears to bear numerous tattoos. Some -- like one of a black sun and another resembling the Iron Cross -- are associated with Nazi symbolism.

"I can say upfront that there are more people involved," the lawyer Dalbon said, adding that "they are not public personalities, they are like this boy."