HALIFAX -- A federal board has rejected the Art Gallery of Nova Scotia's application to certify a multi-million-dollar collection of iconic photographs by famed American artist Annie Leibovitz as "cultural property" of outstanding significance.

The decision is a major blow to the Halifax gallery, which has held the famous portraits in storage for four years, and casts a shadow over the prospects of organizing an exhibit of the photographer's works.

A gallery spokesman says the Canadian Cultural Property Export Review Board concluded that the bulk of the photographs did not meet the criteria for "outstanding significance" or "national importance," crucial for tax incentives for the Toronto family that donated the collection to the gallery.

Colin Stinson says the gallery is "extremely disappointed" and disagrees with the federal board's decision, noting that Leibovitz is one of the most influential photographers of her time.

The collection includes a portrait of a naked and pregnant Demi Moore, a brooding Queen Elizabeth II, and the haunting photo of a naked John Lennon and Yoko Ono cuddling on a floor hours before the musician was gunned down in front of his New York apartment.

It was the gallery's fourth attempt at certification, and officials have said it is likely their last because of time constraints.

Stinson says the gallery's priority is to display the photography, but without the designation that decision belongs to Leibovitz.