The Government is to fast-track new laws to reassure the Russians it is safe to lend Britain its art.
The move is intended to save a landmark exhibition of Russian-held art planned for the Royal Academy in London next month.
James Purnell, the Culture Secretary, today announced that planned legislation intended to give loaned works immunity from seizure will be brought forward, allowing it to be put before Parliament for final consent when the House returns on 7 January.
The show, called From Russia, was under threat after Russian authorities refused to grant an export licence for works held by the country's leading galleries.
The 120 masterpieces from four top galleries and museums, including works by Renoir, Cézanne, Van Gogh, Matisse and Picasso, have rarely been seen outside Russia.
The Russians were worried some works could be seized by the heirs of families who owned them privately until the Russian state requisitioned them after the 1917 revolution. Moscow had accused Britain of failing to promise legal protection for the paintings and demanded more and more guarantees. While Mr Purnell insisted the new laws were not necessary, the legislation - which was due to be made law later next year - will be fasttracked to save the show.
A spokesman added: "The Government has done everything possible to facilitate the exhibition going ahead, including full assurances that the works would be protected from seizure.
"We have also underwritten the collection against loss or damage to the value of nearly £900 million."
The RA would lose millions in ticket sales and merchandising revenue if the show did not go ahead.
The speculation was prompted by Zinaida Bonami, of Moscow's Pushkin Fine Arts Museum, which said they had been told by the Russian federal cultural agency on Tuesday that it would not issue an export licence for the works, which include The Dance by Matisse and Maternity by Gaugin.
The State Hermitage museum, the Russian Museum and the Tretyakov gallery were also denied licences. Federal Culture Agency chief Mikhail Shvydkoi has told Russian TV: "We cannot risk artworks that are part of the Russian cultural heritage."
Descendants of two prominent 19th and early 20th century Russian ar t collectors, Sergei Shchukin and Ivan Morozov, are laying claim to the works.
In 2003 Shchukin's grandson, Andre Marc Delocque-Fourcaud, sued in an unsuccessful bid to remove from the Pushkin's travelling exhibition paintings he claims the Bolsheviks looted from his grandfather in 1918.
The exhibition due to open at the RA on 26 January has faced no problems in Dusseldorf where it is on show. The row had come at a time of hostile diplomatic relat ions between London and Moscow.
This month the Russian government ordered the British Council to suspend its operations outside Moscow, accusing it of operating illegally - a decision Foreign Secretary David Miliband said threatened to damage Moscow's global standing.