Luca Traini, 28, made a fascist salute with an Italian flag draped over his shoulders after the drive-by shooting, which he has since said was motivated by the recent murder of a local woman in Macerata.

A Nigerian drug dealer, identified as Innocent Oseghale, was arrested for the brutal murder of 18-year-old Pamela Mastropietro, whose dismembered body was found in two suitcases.

Mr Traini told investigators that after learning of the Nigerian man’s arrest, he wanted to “avenge Pamela and do something about immigration”.

His lawyer, Giancarlo Giulianelli, said Mr Traini has received numerous messages of support for his actions, pointing to a concerning political problem.

“In Macerata, people stop me to give messages of solidarity with Luca,” he said.

“It’s alarming, but it gives us a sense of what is happening.”

Meanwhile in Rome, a banner reading “Honour to Luca Traini” appeared on Milvian Bridge on Monday night.

The banner was taken down immediately.

Mr Giulianelli said the incident involving his client was “the tip of an iceberg” and that the failure to successfully deal with issues associated with migration was the responsibility of Italy’s politicians.

“Politics hasn’t given an answer to the problem. The right has exploited it, the left has ignored and underestimated it,” he affirmed.

The six victims are from Ghana, Mali and Nigeria, and the attack has been described as a “massacre aggravated by racial hatred”.

Mr Traini reportedly told police he regrets injuring one woman among the six people he struck when he opened fire from his car.