Archivists have hailed an “unprecedented” discovery after long-lost census documents from 1944 detailing Budapest’s 200,000 Jews were found stuffed in a wall during refurbishments.

The trove totalling 6,300 documents was discovered by chance after a workman felt paper jamming a screwdriver through a crack in the wall. Looking inside, they saw what looked like handwriting.

The papers are from the 1944 census, taken two months after the Nazis invaded, and were used to identify 2,000 houses to place Jews before moving them to a planned ghetto in the city’s seventh district.

“The content and scale of the finding is unprecedented,” said Budapest archivist Istvan Kenyeres. “It helps to fill a huge gap in the history of the Shoah here.”