(The Hill) —  Robert F. Kennedy Jr. has apologized for controversial comments he made invoking the name of Anne Frank at an anti-vaccine mandate rally in Washington, D.C., on Sunday that sparked backlash from Jewish groups.

“I apologize for my reference to Anne Frank, especially to families that suffered the Holocaust horrors,” Kennedy wrote on Twitter on Tuesday.  

He said he meant to utilize “examples of past barbarism” to illustrate “the perils from new technologies of control.”

“To the extent my remarks caused hurt, I am truly and deeply sorry,” he added. 

Kennedy spoke at an anti-vaccine mandate rally at the Lincoln Memorial on Sunday. During his remarks, he appeared to suggest that unvaccinated Americans had harder lives than Anne, the teenager who hid from the Nazis in a Dutch attic for roughly two years before being caught and sent to a concentration camp, where she died.

“What we’re seeing today is what I call turnkey totalitarianism. They are putting in place all of these technological mechanisms for control we’ve never seen before. It’s been the ambition of every totalitarian state since the beginning of mankind to control every aspect of behavior, of conduct, of thought and to obliterate dissent. None of them have been able to do it. They didn’t have the technological capacity,” Kennedy said at the rally. 

“Even in Hitler’s Germany, you could cross the Alps into Switzerland. You could hide in an attic like Anne Frank did. I visited in 1962 East Germany with my father and met people who had climbed the wall and escaped, so it was possible. Many died … but it was possible,” he added.

The son of former attorney general and presidential candidate Robert F. Kennedy pointed to low-orbit satellites, 5G technology and digital currency as initiatives he believes the U.S. will “put in place that will make it so none of us can run and none of us can hide.” He also mentioned Bill Gates by name. 

Kennedy’s remarks sparked fierce criticism from Jewish groups, which denounced the comments as offensive while also noting their inaccuracy. Anne sought refuge in an attic in the Netherlands, not Germany. 

“.@RobertKennedyJr invoking Anne Frank’s memory and the mass murder of Jews by the Nazis as a comparison to the U.S. gov’t working to ensure the health of its citizens is deeply inaccurate, deeply offensive and deeply troubling,” Jonathan Greenblatt, the CEO of the Anti-Defamation League, wrote on Twitter on Monday. “This must stop.”

The Auschwitz Memorial suggested that Kennedy’s comments were “a sad symptom of moral & intellectual decay.”

“Exploiting of the tragedy of people who suffered, were humiliated, tortured & murdered by the totalitarian regime of Nazi Germany — including children like Anne Frank — in a debate about vaccines & limitations during global pandemic is a sad symptom of moral & intellectual decay,” the official account for the memorial wrote on Twitter on Sunday. 

The Holocaust Museum sounded a similar note, labeling politically motivated and “reckless comparisons to the Holocaust” as “outrageous and deeply offensive.”

“Those who carelessly invoke Anne Frank, the star badge, and the Nuremberg Trials exploit history and the consequences of hate,” the museum’s official Twitter account tweeted on Monday. 

Kennedy’s wife, Cheryl Hines, also joined the chorus of voices condemning the comments, writing on Twitter that her husband’s reference to Anne “was reprehensible and insensitive.”

“The atrocities that millions endured during the Holocaust should never be compared to anyone or anything. His opinions are not a reflection of my own,” Hines added.

It’s not the first time that Kennedy has referenced the Holocaust in remarks about vaccines. In 2015, while criticizing vaccinating children, he said, “They get the shot, that night they have a fever of 103 [degrees], they go to sleep, and three months later their brain is gone. This is a Holocaust, what this is doing to our country.” Kennedy later issued an apology to “all whom I offended.”

Other critics of vaccine mandates and other COVID-19 mitigation measures have similarly likened such restrictions to Nazi Germany and the Holocaust in the past.

Rep. Marjorie Taylor Greene (R-Ga.) last year compared COVID-19 vaccine and mask rules to the Holocaust before apologizing for the comments. She told reporters she “made a mistake” in making such remarks and apologized.