Historians and members of the public who want to find out more about the Nazi atrocities will be able to browse around two million documents at the new home of the world's oldest Holocaust archive.

The Wiener Library reopened this week at its new location in Russell Square. The Princess Royal was present at the ceremony, which took place more than 71 years after the library was founded by German-Jewish refugee Alfred Wiener, who had fled Hitler's regime for Amsterdam.

It opened in London six years later, on the day that Hitler invaded Poland, and is now home to some 20,000 photographs as well as thousands of pamphlets and newspaper articles, children's board games attacking Jews, and children's books full of crude stereotypes, that could be found in 1930s Germany.

As well as being the world's oldest collection, it is one of the largest and an a valuable resource for researchers. During the libel case involving Holocaust denier David Irving, Deborah Lipstadt's legal team was able to draw on the material for their successful defence.

Thanks to a £475,000 grant from the Heritage Lottery Fund, the library was able to meet its target to equip fully the new premises.

"Some of our items are so old that you can't collect them now," said library director Ben Barkow. "We have them because we were there at the time."