Diana and Callisto by Italian Renaissance master Titian.

Tracey Emin has delivered an artists' petition to Downing Street in a bid to keep two Titian masterpieces in the UK.

Signed by the likes of Lucian Freud, Damien Hirst and David Hockney, the petition says the two 16th Century works have "inspired generations".

The national galleries of Scotland and London hope to raise £50m to save Diana and Actaeon by December 31.

If they are successful, the second painting - Diana and Callisto - will also be offered for sale.

Both of the paintings are being sold by the Duke of Sutherland.

His price is £50m per painting - a third of the estimated open market value.

The artists' petition calls on the government to support the effort to keep the two paintings - which it describes as "among the finest works in private hands in the world" - on public display.

"The paintings 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," the letter states.

"We also believe that, in challenging times, the heritage of the past and the art of the present are more important than ever," it adds.

The paintings were created as part of a cycle of works for King Philip II of Spain from 1556 to 1559.

They form part of the historic Bridgewater collection, owned by the Duke of Sutherland and on display at the National Gallery of Scotland.

The collection also includes three paintings by Raphael, a Rembrandt, a Van Dyck, a Tintoretto and two more Titians.

Titian is acknowledged as one of the greatest colourists of all time who pioneered the use of oil paints and paved the way for generations of artists to come.