An actor who appeared in an award-winning film about child criminals in Naples has been stabbed by an alleged member of one of the Italian city’s “baby gangs”.

Artem Tkachuk, 18, originally from Ukraine, played a young mobster in The Piranhas, which told the story of the phenomenon of baby gangs, criminal groups led by youngsters, in Naples.

The title refers to a word used by the Camorra, the Neapolitan mafia, for the gangs. The film was based on a 2016 novel by the Italian writer Roberto Saviano.

Tkachuk was stabbed in Chiaia, a seafront neighbourhood in Naples, while out with a friend. Tkachuk told police the pair were approached by a baby gang at about 3am on Sunday morning. One of the gang members asked him if he lived in a neighbourhood called Rione Traiano, Tkachuk said, at which point he was stabbed twice in the stomach and his friend was beaten. The wounds were not serious.

Police believe Tkachuk may have been set upon because of his role in the film, directed by Claudio Giovannesi, which won a Silver Bear best screenplay award at this year’s Berlin film festival. Tkachuk played the fictional character Tyson.

Since the early 2000s, Italian authorities have arrested hundreds of Camorra bosses. With the old mobsters either murdered or behind bars, children and young adults have begun taking their place.

Italy’s far-right League party is backing a bill it says will tackle the gangs by lowering the age of criminal responsibility in the country from 14 to 12.

According to Italy’s National Observatory on Childhood and Adolescence, 6.5% of young people in Naples belong to baby gangs. Last summer the city’s court of appeal sentenced 42 members of two gangs from the Forcella and Decumani districts to a combined 500 years in prison.

Saviano’s bestselling non-fiction work Gomorrah, published in 2006, shone a light on the Camorra and resulted in him being granted round-the-clock police protection.