A mystery surrounding the whereabouts of one of the world's greatest works of art, Peter the Great's Amber Room, may have been solved.
The Amber Room has been recreated in Russia
It had been thought that the treasure - erected at a palace near St Petersburg in the mid-18th century - was stolen by the Nazis on invading the Soviet Union.
But new evidence suggests that the Amber Room may have been destroyed by the Russians themselves.
The revelation is made in previously unpublished KGB and Stasi files.
They are included in a new book on the Amber Room by Catherine Scott-Clark and Adrian Levy, which is published on 3 June.
The chamber, crafted from six tons of amber, was erected at the tsars' palace in Tsarskoye Selo, outside St Petersburg.
When the Nazis invaded the Soviet Union in 1941, they wrenched its precious panels from the walls and took them to Konigsberg (the modern Kaliningrad) on the Baltic Coast.
The Amber Room was never seen again, and the Russians have always insisted the Nazis buried or destroyed it.
But an examination of the previously unpublished papers appears to reveal that the Red Army itself destroyed the Amber Room when it stormed Konigsberg in 1945.
The files also suggest that the Russian authorities have known what really happened since the end of the Second World War.
BBC arts correspondent Rebecca Jones said the Amber Room was hailed by those who saw it as the eighth wonder of the world.
Presented as a gift to Tsar Peter the Great in 1716 by Prussia's King Frederick William I, the elaborately carved chamber with its amber panels became a major feature of the Catherine Palace.
Last year Russia announced that work to recreate the room had been completed, weeks before St Petersburg celebrated its 300th anniversary.
Its reconstruction was begun by the Soviet Government in 1979.