Authors claim Vatican censorship of novel

It reads like the plot from a Dan Brown novel: two bold authors unwittingly stumble across restricted Vatican secrets and are then hounded out of Italy by the forces of the Catholic establishment. Which is precisely what Rita Monaldi and Francesco Sorti claim has happened to them.

The husband-and-wife writing team (left) were researching their historical novel Imprimatur when they discovered documents in the Vatican Secret Archive that suggested Pope Innocent XI had paid 150,000 scudi - £3.5m in modern money - to the staunch anti-Catholic Dutch monarch William of Orange in 1672.

William went on to become King of England, Ireland and the Scots in 1689. He is venerated by Ulster protestants for his unremitting hostility towards Rome - today's Orange Orders take their name from him.

The revelation that the Vatican might have helped him in his fight with King Louis XIV of France would be a severe embarrassment to the Catholic Church. So much so, claim Monaldi and Sorti, that the church put pressure on their publishers, Mondadori, not to reprint Imprimatur after its initial print run of 15,000 sold out.

The couple claim that, despite repeated assurances, their publishers quietly shelved their title, and that the subsequent media black-out of the story has led them to flee Italy for Austria. "There is a type of auto-censorship in Italy," says Sorti. "When people know that a subject is risky, they avoid it all costs. Evidently we managed to upset someone senior in the Vatican."

The Catholic Church has dismissed the couple's allegations, a spokesman saying only that their work "managed to sell 15,000 copies in Italy... which is a good figure for that type of book". But an unnamed source at state-owned Italian broadcaster Rai hints at darker forces at play, claiming that the book has become a "taboo".