While being interviewed the 65-year-old actress, who starred in the film adaptation of Dead Man Walking, said she had sent a copy of the book, written by Sister Helen Prejean, to the pope.
reported that, to make it clear that she was referring to Pope John Paul II, Sarandon then said: "The last one, not this Nazi one we have now."
When the interviewer tut-tutted the comment she restated it.
German born Pope Benedict, who was born Joseph Ratzinger, was a member of the Hitler Youth for a short period during the early 1940s. MSNBC
reported that the Vatican said his family rejected Nazi ideology, but membership in the youth organisation was compulsory and he got out as soon as possible.
Catholic League president Bill Donohue said Ratzinger was conscripted into the Hitler Youth at the age of 14.
"Unlike most of the other teenagers, Ratzinger refused to go to meetings, bringing economic hardship to his family," he said in a news release
. "Moreover, unlike most of the others, he deserted at the first opportunity."
Abraham H. Foxman, National Director of the Anti-Defamation League, said he hoped Sarandon would apologise to all of those she might have offended with her words.
"Ms. Sarandon may have her differences with the Catholic Church, but that is no excuse for throwing around Nazi analogies," he said in a press release
. "Such words are hateful, vindictive and only serve to diminish the true history and meaning of the Holocaust."
Public relations expert Glenn Selig said that Sarandon has a reputation for saying things that are controversial, and he does not believe the statement will cause serious damage to her career.
"While inflammatory and insulting to many, particularly Catholics, people know her as someone who speaks her mind. Being opinionated is part of what the public seems to like about her or choose to accept about her, even if they don't agree with her," he told Fox News.
Sarandon is well known for her efforts to battle hunger and AIDS, and was named a UNICEF Goodwill Ambassador in 1999. She has spoken out against the war in Iraq and in support of Occupy Wall Street.