Three letters by Albert Einstein to a group that campaigned against the Nazis in Germany in the 1930s will go on the auction block in Los Angeles next week.

In one of the letters, the father of relativity praises the Friends of Truth, a Cincinnati-based German-American group, for not allowing Jews to join it because it would weaken their anti-Nazi message.

"You're absolutely right not to accept Jews in your ranks, as it would weaken your position. For similar reasons, I have so far avoided speaking out openly about this issue," he said.

Einstein made his home in the United States after Adolf Hitler came to power in 1933.