The National Galleries of Scotland and the London-based National Gallery have successfully bid for Titian's Diana and Actaeon

A £50 million Renaissance masterpiece by Titian has been saved from being sold on the open market thanks to a £17.5 million contribution from the Scottish Executive, it has been claimed.

In August the National Galleries of Scotland and the London-based National Gallery joined forces to buy Diana and Actaeon, Titian's 1550s masterpiece that he painted for King Phillip II of Spain.

The Duke of Sutherland offered the painting to them for £50 million - which experts believe is a knock-down price - on condition they raised their funds by December 31.

Now the Scottish Executive has sealed the deal, according to the Independent on Sunday, which also reported that the National Gallery has promised £12.5 million.

Only two pledges have been made public: £10 million from the taxpayer-funded National Heritage Memorial Fund and £1 million from the Art Fund, a charity.

If the latest report is true, it would mean that at least £40 million will have come from the public purse.

A spokesman for the Scottish Executive said he could not confirm how much it was due to pledge.

An announcement on the potential sale is expected in the next few days, according to those close to the negotiations.

The Duke, 68, who owns a raft of pictures on long-term loan to the National Gallery of Scotland in Edinburgh, called the Bridgewater Collection, said he wanted to sell Diana and Actaeon and a second Titian, Diana and Callisto.

It is understood he wants to diversify his assets, although there has been speculation he wants to sell to avoid his family incurring death duties.

If the consortium is successful in buying the first the Duke has promised to offer the second for the same price.