An American billionaire couple are gifting $115 million of art to the Auckland Art Gallery, the biggest philanthropic gesture of its kind in Australasia.

The 15 paintings and works on paper have been promised by Julian Robertson, who owns golf courses in New Zealand, and his wife Josie.

The art, to be known as the Julian and Josie Robertson Collection, dates from 1875-1951 and includes works by Paul Cezanne, Paul Gauguin, Pablo Picasso, Henri Matisse, Piet Mondrian, Salvador Dali, Georges Braque, Andre Derain, Fernand Leger, Pierre Bonnard and Henri Fantin-Latour.

The two oil paintings by Picasso include one of his most famous Cubist portraits of his mistress Dora Maar, Femme a la resille (1938), and a family study, Mere aux enfants a l'orange (1951), featuring his children Claude and Paloma.

Auckland Art Gallery director Chris Saines announced the Robertsons' "promised gift" last night at a function attended by Prime Minister John Key and Auckland City Mayor John Banks.

A promised gift is a legal pledge which will see some of the works brought to the gallery from the couple's New York apartment for short-term loans on a rotating basis until eventually becoming a permanent part of its collection, currently insured at $320 million.

"The collection will remain with the Robertsons over their lifetimes," said Mr Saines, "although they hope to be able to bring all 15 works to Auckland for a month to coincide with the opening of the developed gallery in April 2011."

The value of the collection is worth more than the gallery's $113 million refurbishment. When it reopens, its Kitchener St rooms will be named the Julian and Josie Robertson Galleries.

"We were thrilled over that," said Mr Robertson, on the phone from New York yesterday. "That was awfully nice but that was the gallery's idea. It wasn't a requirement for the gift."

He said he and his wife had the idea for the gift after the gallery hosted an exhibition of 14 paintings from their New York collection in 2006.

The free show attracted 30,000 visitors in 30 days, and the positive public response via letters and comments, which the gallery sent to the Robertsons, profoundly moved them.

"They were most appreciative of seeing the pictures, more appreciative than anything else we have ever done," said Mr Robertson.

"You fall in love with these pictures a little bit and you want to be sure they will be left with somebody who loves them and that [exhibition] made us realise that they would be loved ... We are really very happy that those pictures are going to be in Auckland for the rest of their time on Earth."

Mr Saines said he had researched the value of major gifts to Australasian art museums and noted that the Art Gallery of NSW received a record-breaking gift last year - of $35 million.

JULIAN ROBERTSON

* Born 1932, Salisbury, North Carolina. Married to Josie.
* Once known as "The Wizard of Wall Street" for his success running his hedge fund firm, Tiger Management.
* Visited New Zealand for the first time in late 1978 with plans to write a novel, which is still in progress.
* Had idea for art gift after Kitchener St gallery hosted an exhibition of 14 paintings from his collection in 2006.
* Developed and owns the Kauri Cliffs lodge and golf course in Northland, and the Cape Kidnappers golf course in Hawkes Bay.
* Forbes estimated his wealth at US$1.8 billion last year.

Sources: Forbes, CNN Fortune, Julian Robertson: A Tiger in the Land of Bulls and Bears.