Martino Stierli, chief curator of architecture and design at the museum, and Ann Temkin, chief curator of painting and sculpture, co-signed a letter to Norway's Prime Minister Erna Solberg expressing their “grave concern” at the building's impending destruction.
The letter asked for her government to “reconsider the approved decision for the demolition”.
The building, they explained, was “a significant example of European brutalist architecture,” designed by the noted Norwegian architect Erling Viksjö, while the murals had marked a new stage in Picasso's career.
“Picasso's murals for the Y-block in many ways signal the beginning of the artist's celebrated works of monumental sculpture that can be found in cities like Chicago and New York,” they wrote.
“As such, the ensemble is a prime example of the notion of a post-war 'synthesis of the arts',” they continued, adding that its removal would mark “a significant loss of Norwegian architectural heritage”.
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Gro Nesjar Greve, the daughter of Carl Nesjar, the Norwegian painter who executed the murals, told the Art Newspaper that the building had been hidden from view since the start of this month.
“The building was fenced in ten days ago, and The Fishermen [one of the murals] was covered up. Workers at the site started drilling, but it’s worrying as once they start moving the mural, it will crack. Nobody has explained how they will do it. The art is the wall.”
Norway's government announced its plan to demolish the Y-block in 2014, three years after it was abandoned after sustaining damage in Anders Breivik's twin terror attack.
A majority of Norway's political parties backed the decision two years later, with plans drawn up to remove the murals and incorporate them into the facade of a new government building.
Norway's Directorate for Cultural Heritage has consistently argued that the Y-block and its neighbouring H-block should be preserved, as has the National Association of Architects. A petition to save the building, started a year, has received nearly 50,000 signatures.