A Jewish leader who survived the Holocaust as a boy by hiding in basements and attics urged countries on Wednesday to speed the opening of millions of files on Nazi concentration camps and their victims.

Leo Rechter, president of the U.S.-based National Association of Jewish Child Holocaust Survivors, told Congress that Nazi war records stored in Bad Arolsen, Germany, should be opened urgently for a dying generation of survivors.

"Of all the public archives in the world, what possible justification can there be to prevent us from learning the truth about what happened to our families during the Holocaust?" he asked, according to testimony prepared for delivery to the House Foreign Affairs Committee's Europe subcommittee.

Rechter, an Austrian Jew whose family fled to Belgium and survived the Nazi occupation after his father was deported and murdered in Auschwitz, spoke at a hearing aimed at stepping up pressure on an 11-nation body that oversees the secret Nazi archive. Wednesday's hearing follows the approval by a House panel Tuesday of a resolution urging the countries to speed up ratification of plans to open the archive to researchers.

This month, the nations overseeing the archive set procedures in motion to open the records by the end of the year. Before the material can be accessed, all member countries must ratify an agreement adopted last year to end the 60-year ban on using the files for research.

The Associated Press, which has been granted extensive access to the archive in recent months on condition that victims are not fully identified, has drawn attention to the importance of the documents.

Witnesses testifying Wednesday expressed frustration that the commission has waited so long to release the files.

"We survivors cannot understand why the world powers would have made a conscious decision to withhold all of the facts about our history from us," said David Schaecter, president of the Holocaust Survivors Foundation.

Some expressed incredulity that the release still faces diplomatic negotiations for final ratification.

"The timetable for this project is not a diplomatic timetable," said Paul Shapiro, director of the Washington Museum's Center for Advanced Holocaust Studies. "Every month of additional delay means more survivors gone — an irreversible benchmark of the consequence of delay."

The State Department said Wednesday that Britain recently joined the U.S., Israel, Poland and the Netherlands in completing ratification.

Germany and Luxembourg have said they would ratify before the commission meets again in May. The positions of France, Belgium, Italy and Greece were unclear.