The internationally best-selling author Robert Harris has written a new book set inside the Vatican during the election of a Pope after being granted access to key locations by the Catholic Church.

Speaking exclusively to Christian Today ahead of the publication of is forthcoming novel, Conclave, Harris revealed that he had been shown around "all the locations that I wanted to see" after writing to the Vatican.

Harris, whose books to date include Fatherland, Enigma, Archangel, Pompeii, Imperium, The Ghost, Lustrum, The Fear Index, An Officer and a Spy and Dictator, said: "I have a lifelong interest in elections and it struck me some time ago that almost the oldest and most important in the world is the election of a Pope." He added: "I felt impelled by curiosity to investigate it. But obviously unlike any other election this is an attempt to find a candidate that God would want and it is that combination of the divine and the secular which is so fascinating. There are so many powerful issues within the Catholic Church and the process of election is a good opportunity to examine them. You have the traditionalists and the progressives."

Little is known so-far about the exact nature of the plot but the publishers, Random House, have released a tantalising blurb which reads: "The Pope is dead. Behind the locked doors of the Sistine Chapel, one hundred and twenty Cardinals from all over the globe will cast their votes in the world's most secretive election. They are holy men. But they have ambition. And they have rivals. Over the next seventy-two hours one of them will become the most powerful spiritual figure on earth."

Harris said: "It has been an interesting and enlightening book to work on". Asked about his own relationship with faith, the renowned author said: "I'm not religious, not a Catholic. I have respect towards faith and with an active imagination have had to get inside the heads of men with faith. I hope I've reflected that adequately."

He added: "I was given some help by the Catholic Church. I was shown all the locations that I wanted to see."

The exclusive corners of the Vatican around which Harris was shown included the Casa Santa Marta, the private residence of Pope Francis and where the Cardinals stay during Conclave; the Pauline chapel, private chapel to the Pope; and the Sacristy of the Sistine Chapel and the 'room of tears' where the new Pope is robed and prays for the first time upon election. Further, Harris stood at the window where a new Pope addresses the faithful in St Peter's Square. He also spoke to a Cardinal who has been involved in the Conclave.

Conclave is published on 22 September simultaneously in the UK, US, Italy, Germany and Holland.