Italian Prime Minister Giorgia Meloni on Tuesday called for "the truth right to the end", while also condemning rioters and defending law enforcement, following the death of a man under police arrest over the weekend.

Moroccan-born Abderrahim Fakir died on Sunday after police pepper-sprayed and restrained him face-down in Bologna's Pilastro district.

A peaceful vigil held for the 42-year-old in Bologna's central Piazza del Nettuno on Monday night turned violent after a separate group clashed with police, reportedly leaving protesters and police wounded.

"Regarding the death of Abderrahim Fakir, it is imperative that any potential causes are thoroughly investigated with the utmost rigour.

"The truth must be pursued without prejudice or leniency for anyone," Meloni wrote in a post published to Facebook on Tuesday.

"But nothing can justify violence against the police", she added, accusing rioters of “fomenting a climate of hatred” against “those who serve Italy every day with professionalism, sacrifice and courage.”

On Monday, prosecutors opened an inquiry into the death of the Moroccan national, who had come to Italy at the age of five.

He died after being restrained by police chest-first on the ground for several minutes.

In a video taken by a resident, Fakir is seen calling for help while pressed to the ground by two policemen and watched by other first responders.

The two policemen and the four first responders are under investigation by the prosecutor.

A demonstration with several thousand people took place on Monday in Bologna, according to images from local media.

Clashes broke out with law enforcement, leaving 64 officers injured, according to the police headquarters.

News channel Sky TG24 reported that eleven protesters were also injured.

Interior Minister Matteo Piantedosi called to wait for the results of the investigation, telling the daily Il Messaggero that "no one is above the law".

The embassy of Morocco in Italy said "it is in the interest of everyone that full light be shed on this tragedy, by establishing the full circumstances of the events with rigour, impartiality and transparency".