Tucked in a small town in central Germany is the world's biggest archive on the fate of millions of Holocaust victims and Nazi era slave laborers. The United States and historians are calling for it to be opened up for research, but claim Germany is refusing to do just that.

Germany has vigorously denied that it is obstructing efforts to give historians access to the world's largest archive on the Nazi concentration camp network and the victims of the Holocaust. A spokeswoman for the Foreign Ministry in Berlin rejected reports of a spat with the United States over the database, which was set up after the war to help families find out what happened to their relatives in the Holocaust.

"The accusation that we are being obstructive is unfounded. Germany is being cooperative and supportive in working towards the opening of the archives," she said on Tuesday.

The New York Times reported that the atmosphere among the 11-nation international commission overseeing the archive had become poisonous and that US government efforts to have it opened were running into legal and procedural obstacles. The German Foreign Ministry spokeswoman said that while the nations agreed on opening the archive, the 1955 "Bonn Agreements" governing its statute would need to be amended because they stipulated that the database must protect the privacy of the information it contained.

"The database contains sensitive and highly personal details about people who are still alive," she said. She added, however, that she was confident the committee would agree to open the archive up and that a working group has been discussing such a move.

The files have been used by the International Tracing Service, an arm of the International Red Cross, to help people trace displaced relatives whom the Nazis sent to concentration camps or used as slave laborers. The United States argues that the archive's tracing role has now largely been fulfilled.

The archive contains documents gathered by Allied forces as they freed concentration camps at the end of World war II. It includes information on what medical experiments were conducted on inmates, what they were accused of, or which inmates collaborated and how they were coerced.

Historians, Jewish representatives in Germany, victims' associations and museum staff at concentration camps have been lobbying for years for the archives to be opened. The database contains information on around 17 million victims of Nazi persecution, and the files extend for over 25 kilometers. They include Schindler's List, according to political scientist Frank-Uwe Betz, who last year published an essay in Die Zeit newspaper calling for them to be opened.

Financed by the German government, the archive is supervised by an international committee consisting of representatives of Germany, the United States, Israel, France, Britain, Greece, Belgium, the Netherlands, Italy, Poland and Luxembourg.

Betz described the center as a "bureaucratic dinosaur." "The huge Holocaust memorial next to the Brandenburg Gate in Berlin may be impressive. But what use is it if the other memorial, the true memorial in Arolsen, remains closed?" he wrote.

Maria Raabe, spokeswoman for the archive, said: "The Bonn agreements state clearly that the archives should not be opened to historical researchers. There are a large number of documents dealing with sensitive issues such as disease, homosexuality or rape." She said the committee would meet in mid-May at the earliest to reach a decision.