An international Jewish organization based in America has denounced US Republican presidential candidate Donald Trump’s claim that dozens of Muslims cheered as the World Trade Center collapsed on September 11, 2001 in New York as unsubstantiated.

“It is unfortunate that Donald Trump is giving new life to long-debunked conspiracy theories about 9/11,” the Anti-Defamation League (ADL) on Sunday said in a statement to BuzzFeed News.

Earlier in the day, Trump said in an interview with ABC News that there were “people over in New Jersey that were watching it, a heavy Arab population that were cheering as the buildings came down.”

The ADL statement said there is no basis for the assertion. “This seems to be a variation of the anti-Semitic myth that a group of Israelis were seen celebrating as the Twin Towers fell.”

“His comments are irresponsible – not to mention factually challenged,” it stated.

Donald Trump speaks during a campaign rally on November 12, 2015 in Fort Dodge, Iowa. (AFP photo)

The September, 11, 2001 attacks, also known as the 9/11 attacks, were a series of strikes in the US which killed nearly 3,000 people and caused about $10 billion worth of property and infrastructure damage.

US officials assert that the attacks were carried out by 19 al-Qaeda terrorists but many experts have raised questions about the official account.

They believe that rogue elements within the US government, such as former Vice President Dick Cheney, orchestrated or at least encouraged the 9/11 attacks in order to accelerate the US war machine and advance the Zionist agenda.