Artificial intelligence technology used to transcribe anonymous historic works at Spain's National Library archives has uncovered a hidden gem - a previously unknown play by one of the nation's greatest authors, Felix Lope de Vega.

The National Library said on Tuesday experts later confirmed that the Baroque playwright and one of the most prominent names of the Spanish Golden Age wrote La francesa Laura (The Frenchwoman Laura) a few years before his death in 1635.

The manuscript stored in the library's archives is a copy that dates back to the late 17th century, long after the author of Fuente Ovejuna and The Knight From Olmedo had died.

Researchers from Vienna and Valladolid universities used AI to transcribe 1,300 anonymous manuscripts and books at the library, saving years of human effort, and also tried to discover their authorship by checking each work against a selection of words used by different writers.

The National Library said the words used in the text were "closely aligned with Lope's, and not with those of the other 350 playwrights who were part of the experiment".

Experts then used traditional philological research resources to corroborate the findings.

"Frenchwoman Laura is a remarkable play, with the dramatic force expected of a mature Lope de Vega," the library said.

The plot, set in France, focuses around Laura, the daughter of the Duke of Brittany and wife to Count Arnaldo. The heir to the French throne is captivated by her, and although she rejects him, her jealous husband tries to poison her. Ultimately, Laura's righteousness is proven and happiness is restored.

Gredos publishing house will release the book in Spanish in the coming months.

 - AP