The Train of Memory, a vintage steam-engine pulling two coaches containing photographs and biographies of child Holocaust victims, began a 1,864-mile educational tour of Germany last November and is scheduled to reach the Auschwitz death camp in Poland in early May. The demand by Deutsche Bahn, the state rail company, and the Ministry of Transport for toll fees is especially controversial for Deutsche Bahn, the successor to the Deutsche Reichsbahn, which willingly collaborated with the Nazi regime and sent millions to their deaths by rail during the Holocaust.

But yesterday Deutsche Bahn said it was bound by law. Susanne Kill, a spokeswoman for the network added: "Deutsche Bahn cannot allow free use of the track in individual cases."

But the angry exhibition's organisers, the Train of Memory group, a privately run organisation, said they had faced resistance to their project from Deutsche Bahn "virtually every step of the way", adding that the "disproportionately large sums" it had to pay in toll fees amounted to "a boycott of this public commemoration".

Hans-Rüdiger Minow, a spokesman for the Train of Memory, said: "We expect to see protests in Germany and abroad until Deutsche Bahn and the Ministry of Transport see sense."

The former Deutsche Reichsbahn used cattle-wagons to transport millions of people, including an estimated 1.5 million children, to the concentration camps. Fewer than 10 per cent survived. The Train of Memory exhibition includes Reichsbahn maps and official documents revealing the company's role in the Holocaust, as well as photographs, poems and poignant letters written by those who never returned. More than 40,000 people have seen the exhibition which has visited more than 40 German towns and cities.

Yesterday was the second time Deutsche Bahn had faced criticism over alleged reluctance to face up to its Holocaust role. In 2006, the company refused to allow another travelling exhibition about the Holocaust to be shown at German stations.

That exhibition, which also focused on the Reichsbahn's Holocaust responsibility, was organised by the veteran Nazi-hunter Beate Klarsfeld and had been shown at railway stations in France. But Hartmut Mehdorn, Deutsche Bahn's managing director, said: "The subject is far too serious for people to engage with while munching a sandwich or rushing for a train."

A Transport Ministry spokesman said Deutsche Bahn was considering donating the toll fees to charity.