Barcenas, who is cited as the most hated man in Spain was reported to police for punching a 59-year-old man after he shouted insults at him, reported Europa Press on Monday.
According to a police complaint, the alleged victim spotted Barcenas in the street on his way back from casting his vote on Sunday at around 6.30pm in the upmarket Madrid district of Salamanca.
As he passed Barcenas, he was moved to mutter: “How you have hurt Spain with your corruption and theft. Have you no shame?”
The reaction from Barcenas was swift, according to the police complaint. He reportedly shouted “Maricon, hijo de puta” - You son of bitch, faggot - before punching the man to the ground and knocking off his glasses.
He then allegedly strolled off, living the victim to stagger to a nearby hospital to seek medical treatment for cuts and bruises.
Barcenas is currently awaiting trial for a long-running corruption probe in financing of the conservative Popular Party. He has admitted running a secret slush fund that handed out undeclared payments to high profile party figures including Mariano Rajoy.
Nicknamed Luis el Cabrón (Luis the Bastard) Barcenas is suspected of having stashed close to €50m in secret Swiss bank accounts.