“The Secret Arias” is based on songs written by Andersen for Jenny Lind, a soprano dubbed the “Swedish Nightingale,” whom the Dane pined for, despite her never returning his affections, said Henrik Engelbrecht, head of dramaturgy at the Royal Theater.

“Elvis immediately loved the idea and when we met him 18 months ago to discuss it, he had already a clear idea about the opera,” Engelbrecht told The Associated Press January 20.

It is believed that Andersen wrote his tale “The Nightingale” with Lind in mind.

The work will open in 2006 in the new opera house’s small experimental stage that can seat 200. The cast hasn’t yet been decided.

After Copenhagen, “The Secret Arias” likely will go on an international tour, Engelbrecht said, and be released as a CD and DVD.

Costello, who has recorded with Swedish soprano Anne Sofie Von Otter and the Brodsky Quartet, will perform the songs in a concert this fall at the new $441 million opera house, which opened Jan. 15.

This year, Danes mark the bicentennial of Andersen’s birth. Andersen is renowned for his children’s stories, including the classics “The Little Match Girl,” “The Ugly Duckling” and “The Red Shoes.” He died in 1875.