NEW YORK - A rare opera by Franz Liszt has been meticulously restored by a scholar, who described the work as unique in the history of music.

The 19th-century Hungarian composer was prolific and won a feverish fan base, but he was best known for his piano pieces and only premiered one opera, a one-act work the prodigy completed when he was 13.

Sardanapale, based on Lord Byron's tragedy Sardanapalo about the overthrow of a peace-loving but hedonistic Assyrian king, was long thought to have been abandoned.

David Trippett, a senior lecturer at Cambridge University, says he discovered the manuscript in an archive in Weimar, Liszt's longtime base in Germany, and spent two years restoring it.

"We will never know exactly why he abandoned his work on the opera and I suspect he would have been surprised to learn that it is resurfacing in the 21st century. But I like to think he would have smiled about it," Trippett says.

Trippett calls the Italian-language opera - which Liszt began in 1849 - groundbreaking as it blended Liszt's characteristic voice with the composer's newfound discovery of Richard Wagner, his contemporary and one of the defining figures in opera.

"The music that survives is breathtaking - a unique blend of Italianate lyricism and harmonic innovation," Trippett says.

Only one act of Sardanapale survives and Trippett says that it was at first barely legible, with Liszt writing in a shorthand that only he understood.

But Trippett says he was able to re-create the piece as it was clear that Liszt "worked out all the music in his head before he put pen to paper".

"To retrieve this music, I've had to try and put myself into the mind of a 19th-century composer, a rare challenge and a remarkable opportunity."

The scholar plans to premiere Sardanapale in June at the BBC Cardiff Singer of the World competition, a leading annual event in Wales.

"Who else gets to premiere a new opera by a superstar composer from two centuries ago?" says US soprano Anush Hovhannisyan, who is taking part in a documentary on the restoration timed for the Cardiff event.

Agence France-Presse