Maria Altmann with a reproduction of Gustav Klimt's 'The Portrait of Adele Bloch Bauer', in January 2004. ((AP Photo/Nam Huh))

Austria will honour an arbitration court decision that five Gustav Klimt paintings, valued at $150 million, should be returned to a California woman.

Culture Minister Elizabeth Gehrer announced Tuesday that Austria would return the paintings, a day after the court ruled they are the property of Maria Altmann.

Altmann, 89, is the niece of Ferdinand Bloch-Bauer, a Jewish sugar merchant who was forced to give up the paintings in 1938 when the Nazis took over Austria.

Altmann says she wants the most famous works, including two portraits of her aunt Adele Bloch-Bauer, to stay in Austria. Klimt's work and especially the famous painting of Adele encrusted with gold leaf, is considered a national treasure.

"I would like the portraits to remain in Austria," Altmann told Austrian state television late on Monday, adding she wanted the landscapes to remain in museums.

Vienna says it can't afford to buy the paintings.

Adele Bloch-Bauer I, also called the Golden Adele, is estimated to be worth between 70 million and 100 million euros ($98 million and $140 million). Some art experts say it is priceless.

"Seventy million euros amounts to the whole budget for all museums in Austria — all public museums," Gehrer told Austrian state radio.

"That means we are not financially able to make purchases here, but talks will be held. Perhaps there are sponsors or the family itself is prepared to make something available as a loan," Gehrer said.

Altmann's attorney, E. Randol Schoenberg, said it was too early to say exactly what would happen to the paintings. Altmann has four siblings who are also heirs with claims to the artwork.

The paintings have been on display in Austria's Belvedere Gallery since 1939.

Klimt was a founder of the Vienna Secession art movement and one of the most prominent painters of the central European version of Art Nouveau.

He painted Adele in 1907 under a commission from her family. She died in 1925 and her husband fled to Switzerland to escape the Nazis.

Austria had claimed in court that Adele Bloch-Bauer left her paintings to the state when she died. After years of legal wrangling, both parties had agreed to abide by the arbitration court's ruling.

The loss of the Klimt paintings would be the costliest concession Austria has made since a 1998 law that ordered all federal museums to review their holdings to see if they included works seized by the Nazis.