A leading Jewish-American organization criticized Pope Francis on Saturday for comparing the refugees camps in Europe that host Syrian refugees to concentration camps during the Holocaust.

Speaking at a special religious service on Tiber Island in central Rome, commemorating modern-day Christian martyrs, Francis said that "these refugee camps — so many are concentration camps, crowded with people.”

"Refugee camps are concentration camps" because they are so overcrowded, the pontiff said.

In response, the American Jewish Committee urged him to take back the statement.

"The conditions in which migrants are currently living in some European countries may well be difficult, and deserve still greater international attention, but concentration camps they certainly are not," said the organization's CEO, David Harris.

He added: "The Nazis and their allies erected and used concentration camps for slave labor and the extermination of millions of people during World War II. There is no comparison to the magnitude of that tragedy.”

Harris noted that "precision of language and facts is absolutely essential when making any historical reference, all the more so when coming from such a prominent and admired world figure.”