THE departing director of the Edinburgh International Festival is working on a new major project – writing an opera set in his native Australia.

Sir Jonathan Mills, who will step down from his post of artistic director of the EIF after his eighth festival in 2014, is to return to composing for his next major event, an opera based on the acclaimed book Eucalyptus by Australian novelist Murray Bail.

The award-winning book is set in rural New South Wales, when a protective father offers the hand of his beautiful daughter in marriage to anyone who can name all the species of Eucalyptus on his property.

The book has rumoured to be in line for film treatment since being published in 1998, with various Hollywood stars, including Russell Crowe and Nicole Kidman, associated with the leading roles.

However, Sir Jonathan will set it for the operatic stage, with six principal singers, a 60-piece orchestra and a chorus, and will work on the piece with Meredith Oakes, the leading Australian playwright and librettist.

Although seen as a "music man", Sir Jonathan, who has a masters in architecture, specialising in acoustic design, received praise early on as festival director for incorporating the visual arts again into the EIF.

In 1995, he began as artistic adviser of the Brisbane Biennial international music festival before becoming artistic director of the Melbourne Festival in 2000-2001 and was vice chancellor's fellow of the University of Melbourne in 2006.

He was the recipient of the Awards Centenary medal of Australia in 2002 and the Prix Italia in 2005.

It has been much discussed what he will do once he leaves his current post, but he is determined to return to his life as a composer.

He will stay in Edinburgh to write the opera, he said, and has no plans to leave the capital even though the 2014 festival, his last, has largely been programmed.

Sir Jonathan will be succeeded by Fergus Linehan, former director of the Sydney International Festival and head of music at the Sydney Opera House.

He said: "Leaving this position gives me more personal space to do things I want to do. Everything I do is rooted in me being a composer, so I can't wait to do this.

"I hope I will have an operational libretto by the end of this year. I will start sketching it next year, and will really throw myself into it in 2015, full time."

He added: "I will stay in Scotland, certainly while I write this opera. Partly because, when you are writing an opera, you need your things around you; you need to know where the corner-store is, where the laundromat is.

"It sounds banal, but when you need to be completely focussed, you cannot move somewhere new."

Sir Jonathan, who was knighted this year, cannot yet reveal who has commissioned the full-length opera, although it is not the EIF, which he said would be "entirely inappropriate".

He said he hopes it will be seen in the UK.

He added: "The reason I wanted to work with Meredith is that, while I don't need an Australian librettist for every project I have in mind, for this one I do.

"Because the book is kind of fantasy love story, a rite of passage, set in an obsessive family in a Eucalyptus forest, unless you have been in a Eucalyptus forest in Australia, with those particular smells, and sights and light and atmosphere, you just cannot capture it."

Sir Jonathan, born in Sydney, has dual citizenship of Australia and the UK as his grandfather was Scottish.

Leaving the post gives me space to do what I want... Everything I do is rooted in being a composer, so I can't wait to do this