Video appears to show Trump mocking the physical condition of a reporter during a South Carolina rally

On Tuesday night at a rally in South Carolina, Donald Trump doubled down on his claim that people in New Jersey cheered after the September 11th attacks 

The real-estate mogul also appeared to mock a journalist for hedging on an earlier report that Trump says corroborates his claim.

At one point during Trump's remarks, the GOP primary frontrunner appeared to imitate the reporter's physical condition.

Former Washington Post reporter Serge Kovaleski suffers from arthrogryposis, a condition which limits the mobility of his arms - a condition Trump seemed to emulate by awkwardly gesticulating while pretending to quote the reporter, as first noted by Ben Schreckinger at Politico.

While Trump's campaign spokeswoman Hope Hicks would not comment on the record to the Post about the incident, a campaign official told the paper that Trump was "not aware of any condition and was not mocking his physical appearance in any way."

However Kovaleski told the Post that he is confident that Trump remembers him and his condition. Kovaleski met with Trump several times when the reporter was covering Trump while working at the New York Daily News from 1987 to 1993.

"The sad part about it is, it didn't in the slightest bit jar or surprise me that Donald Trump would do something this low-rent, given his track record," Kovaleski told the Post.

The New York Times, where Kovaleski is currently a reporter, also had a response to the incident: "We think it's outrageous that he would ridicule the appearance of one of our reporters," a spokeswoman told Politico and confirmed to Business Insider.

During his rally speech, Trump pointed again to a September 18th, 2001 report from The Washington Post, written by Kovaleski and Fredrick Kunkle.

The report, Trump said, was "written by a nice reporter. Now the poor guy - you gotta see this guy. 'Uh, I don't know what I said. Uh, I don't remember!' He's going like, 'I don't remember. Uh, maybe that's what I said.' This is 14 years ago, he's still - they didn't do a retraction!"

In his speech, Trump went on to quote a paragraph from the original report.

"Now, that's The Washington Post. Folks, they do nothing for me, they hate my guys, okay? They don't get it," Trump said, before moving off the topic.

The Washington Post has already responded to Trump's use of the 2001 story as a source for his claims. Kovaleski told The Post, "I certainly do not remember anyone saying that thousands or even hundreds of people were celebrating. That was not the case, as best as I can remember."

Kunkle added to Kovaleski's remarks, "I specifically visited the Jersey City building and neighborhood where the celebrations were purported to have happened. But I could never verify that report."

While Kovaleski did not comment to Business Insider for this story, he did reference coverage of the incident on Twitter, and retweeted a link to a petition by Daily Beast reporter Gideon Resnick calling for Trump to apologize.

Regarding the petition, Resnick told Business Insider that the imitation bothered him. "[T]here's no way to address this besides either acknowledging that it was open mocking and/or deciding to apologize for it. I don't know Mr. Kovaleski personally but I think it's important to hold our serious contenders for public office responsible for their behavior."

Following coverage of the incident and statement by The New York Times, Trump began tweeting about the paper.

Business Insider has reached out to the Trump campaign and The Washington Post for comment and will update if new information becomes available.