Amsterdam - Arson was the cause of the fire that destroyed the barracks where Anne Frank worked during her imprisonment in a Dutch concentration camp during World War II, Dutch police said on Wednesday.

Police said their investigation had ruled out any technical cause for Sunday's fire that virtually destroyed the barracks where Anne Frank, had worked in 1944. No suspects of the fire have yet been detained.

The fire broke out last Sunday, one month before the wooden structure was to return from a farm to its original site at former concentration camp Westerbork.

On Monday, police told the German Press Agency dpa that "several suspicious" fires occurred in the vicinity in recent months. Three investigations were still ongoing. No link could be made yet with the fire at the Anne Frank barracks.

On Monday, the umbrella association for Dutch Jewish organizations CJO called upon Dutch Culture and Education Minister Ronald Plasterk to return all surviving barracks of Westerbork to their original site, to preserve the memory of the Holocaust.

The Westerbork museum had negotiated the return of the particular barracks with the current owner for almost 20 years. The museum recently discovered Anne Frank had worked in the barracks.

Born in Frankfurt in 1929, Annelies Marie Frank, her sister, parents and four other Jews hid in an Amsterdam canal house during World War II. Anne kept a diary during those years.

Only their father Otto Frank survived. In 1947, he published Anne's diary, which had been saved by members of the resistance. The book became an instant publishing success.(dpa)