Author reveals he is already 100 pages into his account of being driven into hiding after publication of The Satanic Verses

Salman Rushdie has revealed that he has already written 100 pages of the memoir that will tell the story of his decade in hiding under the threat of death.

In an interview for his new book Luka and the Fire of Life, Rushdie told Reuters that he was now mid-way through an account of his years spent living under police protection following the fatwa pronounced against him by the then-Iranian leader Ayatollah Khomenei in 1989.

The author said that he had already dealt with around a quarter of the story, and the experience of writing had so far been a good one. "I'm not getting churned up and upset, I'm just writing it and I'm feeling quite pleased to be writing it," he said.

The fatwa requiring Rushdie's execution was issued after publication of his controversial fourth book The Satanic Verses, seen as blasphemous by some Muslims because of its depiction of the prophet Muhammad.

In February 1989, days after a rally at Hyde Park during which copies of Rushdie's book were burned, Ayatollah Khomenei issued the fatwa, urging all "zealous Muslims" to execute the author. The following day he went into hiding with his then wife, the novelist Marianne Wiggins, under the round-the-clock protection of Scotland Yard's Special Branch. The threat of assassination wasn't lifted until 1998, when the Iranian leadership finally modified its position in a move to restore ruptured diplomatic relations with the UK.

It has taken Rushdie a long time to give his personal account of those difficult years. "It's true that there being a kind of information vacuum allows people to speculate or to invent maliciously and that has been a little frustrating," he told Reuters. "But the truth is that until quite recently I was not ready to write this book."

Currently, Rushdie is aiming to finish the memoir – as yet untitled – by the end of 2011, but said that the date will depend on whether the film version of his Booker-winning novel Midnight's Children goes ahead next year. The film of Rushdie's second novel, which was named the Booker of Bookers in 1998, and took the follow-up Best of Booker award in 2008, is to be directed by Indian-born film-maker Deepa Mehta, and Rushdie is writing the screenplay himself.

News this summer that the author was considering writing the memoir prompted an enthusiastic response from booksellers, with Waterstone's spokesperson Jon Howells commenting: "The ironic thing is that this may be his most commercial book in years."