Tracey Emin will today deliver an artists' petition to Downing Street in a bid to save two paintings by the Renaissance master Titian for the nation.
The National Galleries of Scotland and London have until the end of December to raise £50 million to keep Diana And Actaeon in the UK, with the option of buying the second painting, Diana And Callisto, for a similar price in three years.
As part of the campaign to raise funds, a letter signed by luminaries including Lucien Freud, Damien Hirst and David Hockney will be handed to Downing Street, along with a reproduction of the work.
The artists are calling on Government support in their quest to keep the two Titian painting in the UK.
It follows the decision by owner the Duke of Sutherland to sell the paintings.
Gallery chiefs in London and Scotland negotiated to buy one painting jointly for £50 million if they can raise the funds by the end of the year.
They would also be given first refusal to buy the other Titian, Diana And Callisto, for £50 million in three years.
The letter handed to the Prime Minister today states: "The paintings, which are among the finest works in private hands in the world, have been in Britain for more than two centuries on continuous public view at the National Gallery of Scotland since the collection was placed there in 1945, inspiring generations of visitors."
It continues: "The high reputation currently being enjoyed by British art, both at home and abroad, depends on the extraordinary quality and depth of our national collections, which have always been, and remain, a constant stimulus to contemporary artists.
"We also believe that in challenging times the heritage of the past and the art of the present are more important than ever."