It's an unusual bid seeking accountability for alleged war crimes when prosecutors in Kyiv are overwhelmed.

The man asked not to be identified by Reuters for fears for his family's safety still in Russian-occupied areas of Ukraine.

Reuters has seen his near 70-page complaint, filed on Monday (April 15) in the Federal Court in Buenos Aires.

It accuses one named person, two identified by their call signs or military insignia, and others who are unnamed of using electrocution and unlawful imprisonment as forms of torture in mid to late 2022.

"I was detained at work. Then they tortured me. They used electric shocks. It was incredibly painful, so I lost consciousness. I was lucky to survive. Many people are still there."

He alleges 12 to 20 people were held in cells 32-feet squared in the detention center he was held in.

The man's legal team said he was eventually released without charge and fled to safety.

The complaint also contains testimony from other prisoners at the detention facility that support the allegations.

Reuters was unable to independently confirm specifics of the victim's account and the Russian defense ministry on Monday declined to comment.

Moscow denies committing war crimes in Ukraine and has dismissed previous International Criminal Court war crimes arrest warrants as part of a biased Western campaign to discredit Russia.

The man's complaint is supported by members of Ukraine-based NGO The Reckoning Project and legal advisor Tsvetelina Van Benthem.

"It is hoped, of course, that justice will be brought to bear on them, directly. But even if they're just arrest warrants or extradition orders at any particular stage, this will still make the world feel very much smaller for them."

If accepted by Argentinian prosecutors, the case will be the first filed outside of Europe and the U.S. looking at alleged Russian war crimes.

Over 126,000 war crimes cases have been filed since the February 2022 invasion by Russia creating an "unprecedented challenge" for the country's justice system, according to the Prosecutor General's office.

After landmark trials of the leaders of its former military dictatorship, Argentina has become a global leader in universal jurisdiction.

Prosecutors can bring cases for war crimes and crimes against humanity in other countries even if the victims and perpetrators have no link with Argentina.