Russia's announcement yesterday that it had cancelled an important exhibition of French and Russian masterpieces is a heavy blow not only to the Royal Academy but to those who had hoped that the poor state of political relations between London and Moscow would not affect other areas of common interest. After weeks of increasingly polemical accusations, Russia's state cultural agency said that the artworks would not be sent to London because Britain had failed to provide the necessary guarantees that they would not be impounded. This came despite the Government's repeated assurances that the works would be protected against any lawsuit brought by descendants of those who owned the paintings before they were nationalised by the Bolsheviks.

There is, admittedly, a need for a legal guarantee. Five years ago a Swiss judge briefly impounded 55 paintings from the Pushkin Museum as they were leaving Switzerland in response to a suit brought by a disgruntled businessman. Similar threats to confiscate art works have been made in America where émigré families have seen a chance to force compensation for works lost in 1917. Britain is one of the few European countries not to have a law protecting art from seizure, though a new Act is going through Parliament. James Purnell, the Culture Secretary, said yesterday that this would be fast-tracked to guarantee the works before the exhibition opens.

Moscow, however, seems determined on a showdown. The timing alone is suspicious. The Royal Academy show has been planned for two years. The refusal has come at the last moment, timed to cause maximum embarrassment and financial loss: President Putin and Gordon Brown had been invited to contribute to the catalogue, and merchandising plans were far advanced.

Politics, clearly, lie behind the snub. It comes only weeks after Russia ordered the closure of all British Council offices outside Moscow, a move that will affect thousands of Russians learning English, borrowing British films and books and wanting to know more about British life and culture. That move takes Russia back 40 years, when the first British Council teachers were sent into the Soviet provinces. It hits at one of the most basic principles negotiated under the Helsinki accords and reinforced after the collapse of communism: the importance of people-to-people exchanges. Most worrying of all is the explicit linking by Russia of the closures with the Litvinenko affair. This is a throwback to Soviet-style foreign policy, incapable of compartmentalising separate issues and interests. Petty spite seems to lie at the heart of a decision that may be governed as much by Mr Putin's own loyalties to Russia's intelligence agencies, accused of involvement in the Litvinenko murder, as by a determination to demonstrate Russian muscle.

Russia's new culture wars smack of xenophobic nationalism, never far from the surface in both Soviet and Russian politics. Business quarrels are, perhaps, more understandable: the bullying of big investors such as Shell and BP is unpleasant but points mainly to a crude attempt to wring maximum advantage from Russia's energy dominance. From Kosovo to Iran there is much that Moscow and London need to work on together. But a refusal to maintain cultural links, hugely important to most educated Russians, is as sad as it is ominous for future relations.