A letter written by Albert Einstein in June 1939 about the dangers faced by Jews in Nazi Germany has been sold for almost $14,000 (double the expected price) at an auction in California.

According to reports, Einstein (who had fled Germany for the U.S. in 1933 when Adolph Hitler became the Chancellor), wrote the typed missive to New York businessman Hyman Zinn to thank him for assisting Jews seeking to escape Nazi Germany.

In the letter, the Nobel Prize-winning physicist, wrote in English: “It must be a source of deep gratification to you to be making so important a contribution toward rescuing our persecuted fellow-Jews from their calamitous peril and leading them toward a better future.”

He added: The power of resistance which has enabled the Jewish people to survive for thousands of years has been based to a large extent on traditions of mutual helpfulness. In these years of affliction our readiness to help one another is being put to an especially severe test. May we stand this test as well as did our fathers before us.

The letter, which was described as being in “very good to near fine condition, was sold at the Los Angeles auction house Nate D Sanders and contained Einstein's embossed Princeton University address and the original mailing envelope.

In a statement, Sanders said: “This historical letter contains powerful content showing that Einstein was devoted to the Jewish people.”