People walk past a poster advertising the forthcoming exhibition 'From Russia : French and Russian Master Paintings 1870-1925' outside the Royal Academy of Art in London. Photograph: Sang Tan/AP
The Royal Academy of Arts was tonight desperately seeking clarification over the future of its planned blockbuster exhibition of Russian and French masterpieces.
The status of the exhibition remains uncertain after it was announced that Russia had withdrawn its loans of the paintings.
Russia is saying loans from its museums - which include works by Renoir, Cézanne, Van Gogh and Picasso - will not go ahead unless Britain steps up its legal protection of the paintings.
The London exhibition was one of the most keenly anticipated of the year. It was due to include works from the Hermitage museum, in St Petersburg, which have never been exhibited in Britain before and are insured for almost £1bn.
In an attempt to save the exhibition, the government announced today that it was bringing forward new legislation intended to ease the Russian concerns.
The Department for Culture, Media and Sport said it would fast-track "immunity from seizure" laws to cover the paintings the Russians have threatened not to lend the show.
This afternoon, the Royal Academy said it still had not yet received any official notification regarding the status of the exhibition - entitled From Russia: French and Russian Master Paintings 1870 - 1925 from Moscow and St. Petersburg - and was seeking clarification with the Russian ministry of culture. The show had been due to open next month.
Russian officials said they wanted more protection from individuals who might claim the works had been looted from their families during the 1917 Russian Revolution.
The new legislation is designed to bring Britain's laws in line with the rest of Europe, including Germany, where many of the paintings are currently on display.
It means descendants of the original owners cannot bring their claims on British soil.
A spokesman for the Department for Culture, Media and Sport said: "The immunity from seizure legislation would not have been in force in time to cover this exhibition.
"Due to the special circumstances of this case and the importance of this exhibition we are bringing this forward to be enacted on January 7. We believe that there can be no further obstacles to the loans taking place."
The unexpected move by Russian officials to withdraw the loans was seen as having little to do with art and everything to do with worsening relations between the two countries since the murder of the former Russian spy Alexander Litvinenko.
Litvinenko died in a London hospital after being poisoned with polonium-210, a rare radioactive isotope.
A Russian culture official said a final decision on lending the pieces would be made today.
The culture secretary, James Purnell, told BBC Radio 4's World at One: "If the concern is about the return of the pictures, we believe that this is a belt and braces approach which gives them every guarantee that they require."
The RA last night it still expected the 13-week show to go ahead.
Although now regarded as some of Russia's greatest treasures, many of the paintings were seen as suspect and decadent in the wake of the Russian Revolution, despite being nationalised and declared part of the state collection.
The single most famous work, Matisse's La Danse, was commissioned direct from the artist by the textile millionaire Sergei Shchukin to decorate his Moscow home.
When he first saw it, he was said to have considered sending it back to be made more decent because he was worried the ecstatic naked figures would shock his young daughters.
His grandson has lodged a series of unsuccessful claims to this and other pictures from the collection, in Paris, Rome and Los Angeles.