Adele Bloch-Bauer II by Gustav Klimt.

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It follows on from the private deal the auctioneers brokered earlier this summer that saw Klimt's 1907 portrait Adele Bloch-Bauer I become the most expensive painting ever sold when it was purchased by cosmetics magnate Ronald Lauder, founder of Neue Galerie in New York, for $135m (£77m).

All five works are currently on view at the Neue Galerie in an exhibition that runs until September 18.

It has been widely reported that the four pictures, Adele Bloch-Bauer II, Apple Tree I, Birch Forest and Houses in Unterach on Lake Atter, will appear in the saleroom, but a spokesman for Christie's was unable to confirm this to ATG. "A sale plan is just being devised at the moment," she said. "It hasn't yet been decided whether they'll be sold at auction or by private treaty. We hope to make an announcement in the next few weeks."

The works were the subject of a six-year legal battle between Maria Altmann, the 90-year-old niece of Adele and Ferdinand Bloch-Bauer who originally owned the pictures, and the Austrian government. They were confiscated in Vienna in 1938 by the Nazis, and were eventually placed in the city's Gallery Belvedere.

The case came before the Supreme Court in the US in 2004, but it was eventually an Austrian arbitration panel that ruled in January this year that the paintings should be restored to the Bloch-Bauer heirs.

Reports have now emerged from Vienna that a prominent businessman may step in to help bring one or more of the pictures back to Austria, having expressed an interest in Houses in Unterach on Lake Atter estimated at $25m.

By Alex Capon