First he took on the Mafia – now Saviano battles the Berlusconis

One is the powerful daughter of the Italian Prime Minister who runs his publishing empire; the other is the country's best-selling author, and not for the first time a simmering feud between the two has boiled over.

Aside from the clout that Marina Berlusconi and Roberto Saviano both wield, the row is remarkable because Mr Saviano, who won worldwide recognition for his book Gomorrah – adapted for an award-winning film in 2008 – is the leading author at the Berlusconis' Mondadori publishing house, which Ms Berlusconi runs.

A series of bitter exchanges dates back a year after an incident in which Mr Saviano, 31, openly backed Milan's magistrates in their attempts to bring the Prime Minister to book. Ms Berlusconi, 44, said she was "horrified" by those comments, and the relationship between the publisher and star writer has been rocky ever since.

This week Mr Saviano, who is under 24-hour armed protection following his exposé of the Naples mafia, published his latest tome, Come Away With Me, with the rival publishing company Feltrinelli. And on Sunday evening, the Naples-born writer couldn't resist another poke at Ms Berlusconi, who also chairs her father's Fininvest holding company and who has been ranked the 33th most powerful woman in the world by Forbes magazine.

Interviewed on the Che tempo che fa? television show, Mr Saviano accused her of having a record of defending the Prime Minister rather than supporting her writers. But she hit back, slamming his "by now tedious polemics", adding that "freedom of expression was a universal right" and that he was "confusing criticism with censure".

Yet round three went to the author: "If you say that to defend magistrates is something horrible and that to write about the mafia is a way of defaming Italy, are you speaking as a publisher or as the daughter of Berlusconi?" he said.

As with most high-profile public spats in Italy, the row can be traced back to the Prime Minister himself, and comments he made last April accusing the author of giving publicity to the mafia.

Critics were not slow to note the evidence of Mr Berlusconi's own links with organised crime. Cosa nostra hitman Vittorio Mangano worked for Berlusconi as a stable master at the mogul's villa near Milan in the 1970s.

And there has been much speculation about the origins of the Berlusconi family's vast wealth. Last year the Sicilian senator – and key Berlusconi political associate – Marcello Dell'Utri was imprisoned for seven years for his mafia associations.

Marina Berlusconi remains fiercely loyal to her father, who is facing the imminent resumption or start of four trials on charges ranging from sex with a minor to tax fraud. There has been some speculation that she might soon enter politics to carry on the Berlusconi dynasty. Her ability as a canny businesswoman is not in doubt, however. She and Mr Saviano might even be seen as the best of enemies, given the millions of euros they have made together.

Sure enough, one of her top executives, Riccardo Cavallero, said yesterday he hoped Mondadori would publish more books by Mr Saviano in the future. "Saviano is and will be an important author for our company," he said.