By Geraldine Coughlan BBC News, Amsterdam

The exhibition includes letters to family and friends

A special exhibition of private letters written by Anne Frank has opened at the Amsterdam Historical Museum.

Almost everyone is familiar with Anne Frank - the Jewish girl whose diary of life in hiding in Nazi-occupied Amsterdam made her world famous.

But now her private letters reveal more about her independent spirit.

One is a letter Anne wrote to her father who was not happy about her friendship with a boy who shared her hiding place.

Most of the others were sent to her relatives in Switzerland.

Wouter van der Sluis, curator of the exhibition, said the letter to her father was a declaration of independence, which Anne believed had been destroyed.

Because she's world famous you want to know everything about her and indeed you find something more about her reading those letters Wouter van der Sluis

"In that letter she said, through all this heavy circumstances here I've grown up earlier," he said.

"Her father was very displeased with that letter and he said in a talk with her, 'I'm going to burn that letter', so we always thought it was burned. But all the time it was waiting for us after the war in the archives of the National War Institute here."

But why are these letters - written by a girl who is already a world famous author - so important?

"Because she's world famous, you want to know everything about her, and indeed you find something more about her reading those letters," said Mr Van de Sluis.

"For instance, she had a Jewish upbringing, and more than we thought. We thought she was completely secular but she wasn't. She had Jewish lessons she followed in the Jewish synagogue here in Amsterdam."

Immigrant contribution

The Mayor of Amsterdam, Job Cohen, is Jewish.

At the preview of the exhibition, he spoke of Anne as an immigrant who came here as a refugee. He said the cultural contribution of immigrants must not go unnoticed.

More details about the young girl's life and personality are revealed

Anne's letters have already made an historic impact in the city where she sought refuge and was betrayed.

The exhibition shows photos of the Frank family home in Amsterdam before the Nazi occupation. It has now been restored to house refugee writers, poets and journalists who cannot work freely in their country of origin.

One picture shows Anne aged 13. She wrote to her grandmother: "Here I am sitting at the writing desk".