Ben Carson. (Melina Mara/The Washington Post)

This story has been updated.

PAHRUMP, Nev. — Republican presidential candidate Ben Carson on Monday walked back the claim that he had seen highly disputed footage showing thousands of Muslims in northern New Jersey celebrating the collapse of the twin towers following the 9/11 terrorist attacks, releasing a statement just hours after his initial remarks to clarify what his campaign called a mistaken reference.

"He doesn't stand behind his comments to New Jersey and American Muslims," Carson spokesperson Doug Watts told ABC News. "He was rather thinking of the protests going on in the Middle East and some of the demonstrations that were going on in celebration of the towers going down."

GOP front-runner Donald Trump has made the same claim, but no such video has emerged and fact checkers and news anchors on assignment at the time have said such footage does not exist.

“I saw the film of it, yes,” the retired neurosurgeon told reporters Monday during a news conference at the Pahrump Nugget casino and hotel. Another reporter followed up immediately to clarify: "In New Jersey?" Carson responded affirmatively; he later repeated that he saw the celebrations in "the newsreels" at the time.

“There are going to be people who respond inappropriately to virtually everything. I think that was an inappropriate response,” Carson added. “I don’t know if on the basis of that you can say all Muslims are bad people — I really think that would be a stretch.”

An extensive review by The Washington Post following Trump’s claims did not turn up any evidence of mass celebrations within the United States. The Carson campaign did not immediately respond to a request for related footage.

"He doesn't stand behind his references and apologizes for the mistaken references. It was a mistake on his part and he clearly wasn't really thinking about New Jersey, he was thinking about the Middle East," Watts told ABC.

The misstep comes as Carson and Trump have both faced mounting criticism for calling on expanded surveillance of Muslim Americans in the wake of the terrorist attacks in Paris that left more than 100 people dead and hundreds more injured. On Monday, Carson elaborated on his calls for closer monitoring of mosques.

“If we have evidence that there is radicalization going on — and the point that I’m making is that it doesn’t have to be specific to a mosque; it can be anything. It can be this place where we are right now,” he said. “If there are multiple reports and indications that radicalization is going on there, we shouldn’t just turn a blind eye to that.”

During the media availability, Carson also repeated previous calls for the government to expand the FBI’s surveillance capabilities to monitor for potential terrorist activity. When asked about his recent claim that the FBI can only monitor between 30 and 60 people at a time, Carson qualified the statement by saying that’s the number of people the FBI “can follow 24/7, not just people on their watch list.”

When asked where he received that information, he said: “From television. The same place the president seems to get most of his information,” Carson said. He then turned the question on reporters: “So you guys better be accurate.”

Carson did not elaborate on what the monitoring would entail. He dismissed a question regarding privacy rights.

“No, I don’t worry about that,” he said. “The thing that will destroy our country is if we are overly concerned about violating somebody’s sensibilities while we allow blatant activity to occur that will violate all of our sensibilities.”

Carson added that he holds “the Constitution to very high regard. I think that everybody is protected by it. It’s there to outline what our rights and protections are as citizens, but it’s also there to constrain the government.”