Records about cultural artefacts which were looted by Nazis during the Second World War are to be published online so families and historians can trace artworks which have gone missing.
An international archive is to be created so that the lineage of plundered items can be traced. More than 950 documents from the National Archives will be contributed to the catalogue, a spokesman said.
The records, dating from 1939 to 1961, document the systematic looting of Jewish households by Nazi agencies, Hitler's plans to establish a Fuehrermuseum with the seized art in his hometown of Linz and the role played by art dealers in securing and trading looted artworks in Nazi-occupied Europe.
The files range from inventories and images of seized works of art, interrogation reports of art dealers and inventories of claimed property.
They also detail efforts to identify and recover the articles during and after the Second World War.
The National Archives and the Commission for Looted Art in Europe signed an agreement to provide the documents to the international archive.
Chief executive and keeper of the National Archives, Oliver Morley, said: "It's a privilege to be involved in this unique global collaboration - working together with leading archives throughout the world to make these records more accessible on an international scale.
"By digitising and linking archival records online, researchers will be able to piece together the stories of what became of cultural objects, be they books, paintings, sculpture, jewellery or any other stolen artefacts from evidence fragmented across borders and languages."
Anne Webber, co-chair of the Commission for Looted Art in Europe, added: "For the first time in searching for the many thousands of still missing objects it will be possible to trace their fate online through these records which provide the names of victims, perpetrators, artists and works of art.
"The records and history they represent have never been made internationally available before and this project represents a major step forward in international co-operation to help resolve these long outstanding issues."