A temporary export bar has been placed on a £10m painting by one of the UK's most celebrated artists, JMW Turner.
The masterpiece, The Dark Rigi, the Lake of Lucerne, depicts a scene in the Swiss mountains - but there are fears it could be exported for sale abroad.
Arts minister Rebecca Pow said it would be a "terrible loss to the whole country" if the painting went overseas.
The export ban runs until 1 December, in the hope the money can be raised to buy it and keep it in the UK.
The famous work, a watercolour painted in 1842, is the only remaining work from the Rigi series - Turner's three paintings of the Rigi mountain - which is not in a public collection.
Ms Pow said: "Turner is one of Britain's greatest ever artists and The Dark Rigi is a beautiful and emotive work painted at the pinnacle of his career.
"This work is of national importance and if it were to go abroad it would be a terrible loss to the country.
"I hope that by placing a temporary export bar, we can ensure that funds can be raised to save The Dark Rigi for the nation so it is able to go on public display."
Ms Pow, who has been in her current post since May, made her decision after advice from the Reviewing Committee on the Export of Works of Art and Objects of Cultural Interest.
The committee's job is to advise the government on exporting cultural property.
For example, if an artwork is sold to a foreign buyer, it can suggest delaying the granting of an export licence to allow time for a British buyer to raise funds to buy the work instead and keep it in the UK.
The decision on the export licence applications for the watercolour has now been deferred until 1 December.
If a serious intention is made to raise the £10m funds to purchase the artwork, the export bar may be extended until 1 June 2020.
Turner, who was born in London in 1775, is considered one of the greatest figures in the history of landscape painting.