An academic who described a novel about the Prophet Mohammed as "softcore pornography" has faced calls to apologise after the home of the publisher was targeted in a suspected petrol bomb attack.

Martin Rynja, whose Gibson Square publishing house will release The Jewel of Medina in the UK next month, is under police protection following the incident in Islington, north London, in the early hours of Saturday morning.

The book, by American author Sherry Jones, focuses on Mohammed's relationship with his young bride Aisha, and publisher Random House cancelled publication of the book in the US earlier this year saying it had heard from "credible and unrelated sources" that the work "could incite acts of violence".

Denise Spellberg, an associate professor of Middle Eastern Studies at the University of Texas, was quoted in the US media as saying The Jewel of Medina took "sacred history" and turned it into "softcore pornography".

Ms Jones' agent Natasha Kern said the novel was not offensive, and having the public read it was the only way to counter the "distortions and outright lies that the book either insults Mohammed or contains salacious or suggestive material".

The novel is "peace-building and bridge-building", Ms Kern added, and will encourage dialogue between Muslims and non-Muslims.

Mr Rynja, 44, was not hurt in the incident, in which an accelerant was lit in the doorway of his home which doubles as the office for Gibson Square.

Neighbours described seeing smoke and flames in the doorway of the house.

"I think she (Prof Spellberg) should come out and apologise to Martin Rynja, because he's been endangered precisely because of what she said," Ms Kern said.

Two men were arrested outside the Lonsdale Square property on terror charges in the early hours of Saturday, while a third was detained outside a nearby Underground station.

The three men, aged 22, 30 and 40, were detained on suspicion of the commission, preparation or instigation of acts of terrorism, and are being questioned at a central London police station.

Officers also searched four addresses around north-east London - two in Walthamstow, one in Ilford and one in Forest Gate.

Mr Rynja himself was unavailable for comment but, announcing the book's publication earlier this month, he said: "In an open society there has to be open access to literary works, regardless of fear. As an independent publishing company, we feel strongly that we should not be afraid of the consequences of debate.

"The Jewel of Medina has become an important barometer of our time."

By Damon Wake