Moscow on Thursday cancelled a much-awaited exhibition of precious paintings in London, saying Britain had failed to guarantee the works' safe return, as a diplomatic row between the two countries spilled into the art world.
Britain failed to persuade Russia to loan the 120 masterpieces by French and Russian painters, including Matisse's iconic "The Dance", said the head of the Federal Agency for Culture and Cinematography, Mikhail Shvydkoi.
A letter was sent to the British government declaring it was "impossible to accept as sufficient the guarantees of the exhibition's (legal) immunity and the return" of the artworks to Russia.
The exhibition, "From Russia: French and Russian master paintings 1870-1925," was scheduled to open January 26 at the Royal Academy of Arts. It would have featured works from four Russian museums by Gauguin, Matisse, Renoir, Van Gogh, and Russian artists.
Britain says it had provided all necessary legal guarantees.
Moscow's refusal to take London's word was the latest shot in a diplomatic war that escalated after the murder last year of a fugitive Kremlin critic given asylum in Britain.
A failed attempt by Britain to extradite the chief suspect, ex-KGB officer Andrei Lugovoi, prompted tit-for-tat expulsions of diplomats this July.
Then last week Russia announced it was closing down regional offices of the British Council. Moscow accused the cultural organisation of having failed to register properly, a charge British Prime Minister Gordon Brown angrily denied.
Russian officials insist the row over the art exhibit is purely a legal matter, not political.
However, Foreign Minister Sergei Lavrov made a clear link last week between the British Council dispute -- which is also outwardly a technical matter -- and the Litvinenko affair.
"This is retaliation," Lavrov said. "It's the law of the genre, if you wish. When they expelled a few Russian diplomats... they were inevitably calling for retaliation."
James Nixey, a Russia expert at the Royal Institute of International Affairs, said President Vladimir Putin was deliberately provoking fights to demonstrate his country's newfound toughness.
"They are after recognition and respect. They are after power projection. To be a big player that plays with the big boys: that's ultimately it. It's little steps that build up as part of a master plan."
Russian art experts say Moscow particularly fears legal challenges in Britain by descendants of tsarist-era Russians whose families are reported to have owned some of the art works until they were confiscated in the Bolshevik Revolution.
Shvydkoi said that Russia would send the exhibition "immediately" if the British government guaranteed that "a decision by any British court on impounding the exhibits will be fulfilled only after their return to the Russian Federation."
London has all along inisted that the necessary conditions were being met for the works, which were to be loaned from four Russian museums, including the State Hermitage Museum and the Pushkin Museum of Fine Arts.
"Thousands of works of art are lent to exhibitions in the UK each year from foreign institutions, including Russia," a spokesman for the Department of Culture, Media and Sport said Wednesday.
On Thursday the culture ministry appeared caught unawares by the Russian announcement.
"They certainly haven't told us that," said a spokesman. "At the moment our position remains the same. A number of letters have been sent from this department... giving them all the chances that we believe we are able to."