Diners at the pre-auction champagne-and-caviar launch on Saturday night at Sotheby's found themselves sitting alongside dozens of previously unseen Faberge pieces. London conceptual artist Grayson Perry, dressed in a black taffeta version of his trademark 'little girl' attire, was seated in view of Aivazovsky's 1886 painting The Wrath of the Seas, (left). Recognised as one of the greatest Russian painters, Aivazovsky's work is rarely seen outside the state collections in Moscow and St Petersburg. It fetched £513,000 last night.

So who is coughing up these breathtaking sums? Aivazovsky's emigre compatriots, of course. A Sotheby's source said of this week's event: "Ninety-nine per cent of the buyers in London this week will be Russian."

Russian art bought by Russians outside Russia is becoming one of the biggest stories in the art world. A similar sale by Sotheby's in New York earlier this year surpassed all records and raised more than $50m. Russian art is Sotheby's fastest-growing market - they have sold over $100m worth of Russian art in 2007 and opened an office in Russia earlier this year.

The highlight was Bluebells by Natalia Goncharova which fetched £3m

What's interesting, however, is that few if any of the pieces waiting to be snapped up in London are likely to return to Moscow anytime soon. Rich Russians abroad are constantly fearful that their assets might one day be seized by the state. On top of that, should an owner want to bring the art out of Russia again, border officials are notoriously corrupt.

Most of the works on sale at Sotheby's came from outside Russia anyway, from private collections in the US and Germany. Now they will simply be held in Russian private collections abroad. "Most of them are buying for their homes and
collections abroad - they are not interested in getting this artwork back into Russia. That's just too risky," I was told.

The transport of Russian art across borders is always a difficult issue. The Royal Academy's forthcoming exhibition From Russia: French and Russian Master Paintings 1870 to 1925, due to open in January, has been dogged by rumours that many Russian museums do not want to release their best pieces, in case they are impounded while abroad. Perhaps this week's sales will help - as should Putin's planned visit to the opening of the RA show, alongside Gordon Brown.

Art has become a serious investment and a matter of pride for Russians. At Saturday's dinner a group of surly oligarch types could be heard growling over a set of Malevich prints: "They're worth a lot more than £100,000."