posted January 25, 2007 05:39 PM              

The YIVO Institute for Jewish Research, a New York-based institution that focuses on the history and culture of Eastern European Jews, said Thursday it had discovered the file among 100,000 other Holocaust-related documents about a year and a half ago. The institute did not immediately disclose the find because it had to explore copyright and other legal issues, she said.

"We have come across the file which belonged to Otto Frank, documenting his efforts to immigrate his family and get them out of Holland," said Cathy Callegari, a spokeswoman for YIVO.

On Feb. 14, she said, the institute will release Frank's letters and documents and records from various agencies that helped people immigrate from Europe.

The disclosure came as a surprise to Bernd "Buddy" Elias, Anne Frank's cousin and the president of the Anne Frank Foundation in Basel, Switzerland. The organization, established by Otto Frank, holds the rights to Anne Frank's writings, according to its Web site.

"We would love to have them in our archive. I mean, we are the heirs of Otto Frank," Elias told The Associated Press.

Callegari said the documents include letters that Otto Frank wrote to relatives, friends and officials between April 30, 1941, and Dec. 11, 1941, when Germany declared war on the United States.

The Frank family's hiding place in a secret annex in an Amsterdam canal-side warehouse has been turned into a museum.

Patricia Bosboom, of the Anne Frank House museum in Amsterdam, said officials there had heard about the discovery of the letters but had not seen them. But she said they would fit with the general picture that's known about Otto Frank's many efforts to get the family out of Europe.

Written when the U.S. consulate in the Netherlands had closed, the letters show how Otto Frank investigated potential escape routes through Spain to Portugal, attempted to secure visas to Paris and tried to arrange for his family to go to the United States or Cuba.

His attempts to arrange a route out of the Netherlands were unsuccessful. The family took refuge in July 1942, hiding for more than two years before being arrested. Anne Frank described the family's life in hiding in a diary that has sold an estimated 25 million copies.

The letters were initially held by the New York City-based Hebrew Immigrant Aid Society, which gradually transferred its archives to the YIVO institute between 1948 and 1974. Callegari said a volunteer archivist at the YIVO Institute discovered Otto Frank's letters about a year and a half ago.

Anne Frank died of typhus at age 15 in a concentration camp at Bergen-Belsen, Germany, in 1945. Her father returned to the Netherlands to collect his daughter's notes and published them in the Netherlands in 1947.

Time magazine first reported on the newly discovered documents on its Web site Thursday.

Associated Press writers Frank Jordans in Geneva and Toby Sterling in Amsterdam contributed to this report from Geneva.