A Jewish academic has shocked Italy by claiming Jews murdered Christians for their blood in the Middle Ages so it could be used in rituals.
The details were revealed in the Italian newspaper, the Corriere della Sera, which published extracts of the book, Easter of Blood by Professor Ariel Toaff.
The claims were denied by leading Jewish figures including his father Elio, once the chief Rabbi of Rome.
In the book, Prof Toaff alleges the ritual killing was carried out by members of a fundamentalist group in reaction to the persecution of Jews.
The book describes the mutilation and crucifixion of a two-year-old boy to recreate Christ’s execution at Pesach, the Jewish Easter. The festival marks the fleeing of the Jews from Egypt and Prof Toaff says Christian blood was used for "magic and therapeutic practices".
In some cases the blood was mixed with dough to make azzimo, unleavened bread, eaten at Pesach.
He says the acts took place in around the city of Trento in modern northern Italy, between the 11th and 14th centuries.
Prof Toaff based his book on confessions he says came from Jews captured and tried for the practice. He said several were executed after confessing to the crucifixion of Christian children.
Italy’s senior rabbis, including Elio Toaff, issued a joint statement condemning the book.
"There has never existed in Jewish tradition any permission or custom for using human blood for ritual purposes. Such a practice is considered with horror.
"It is absolutely improper to use centuries old statements, extracted under torture, to formulate singular and aberrant historical theses. The only blood shed in these stories is that of many innocent Jews."
Prof Toaff, who teaches mediaeval and Renaissance history at Bar Ilan University in Jerusalem, said the reaction was a "disgrace" as they had not read the book, which has yet to be published.
He emphasised the practice was confined to "a small group of fundamentalists."
He added that attacking the whole of Judaism would be similar to blaming Islam for the acts of extremist Muslims.
"They had suffered from the trauma of mass suicides. [sic] It was both a kind of revenge and a way, for them, of seeking redemption."