Arts chiefs have renewed their calls for tax reforms to enable masterpieces to be saved for the nation in response to the threatened sale of two Titian paintings on loan to the National Galleries of Scotland.

Canada, Australia, France, Spain and the US each allow owners to receive rebates on income tax. This encourages them to gift art works to public galleries and museums as “living donors”.

Experts are appealing for the introduction of a similar system in Britain. At present, the UK Treasury offers tax concessions only after the owner has died. An attempt to introduce income tax changes to encourage donation were rejected in 2005 by the then Chancellor, Gordon Brown.

The renewed demands came after it was revealed that the Duke of Sutherland is hoping to sell two important Titian paintings, Diana and Acteon and Diana and Callisto, which have been on loan to the NGS since 1945.

The Duke has offered them to the nation at a discounted price of £100million, but they will be sold for up to £300million on the open market if half of the money cannot be found by a deadline of New Year's Eve.

David Barrie, director of the Art Fund, a charity which raises money to buy paintings for public display, said: “We need a system of income tax reliefs to encourage donors to give art works to museums and galleries during their lifetime. If you could cultivate relationships with donors while they are alive, you could develop collections in a much more strategic way.”

In 2005 the cross-party Culture, Media and Sport Committee at Westminster recommended income tax changes to boost donations of art, but the Treasury turned down the proposal. “There is an endemic resistance in the Treasury to changes in the income tax system,” Mr Barrie said.

“There is a suspicion that it only benefits toffs. There are now many people with a couple of nice pieces that they cannot afford to give away completely, but would if they were incentivised to do so.”

Among those who support an income tax-based scheme are Sir Nicholas Serota, director of the Tate Gallery, Mark Woods, chairman of the Museums Council, and John Leighton, director of the NGS. They believe that potential philanthropists are too young to defer tax benefits until their death. Mr Leighton said: “There is potential for a whole new wave of philanthropy if there were better incentives for lifetime donations.”

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