El Museo del Barrio has apologized for renting its space to an organization whose four-day event promoted 9/11 conspiracy theories, including claims that the Twin Towers were brought down by controlled demolition rather than the hijacked planes.

The event, titled "Turning the Tide: 9/11 25 Years Later," ran from September 10 to 13 and marked the 25th anniversary of the attacks on the World Trade Center. The International Center for 9/11 Justice organized it. The group's stated goal, according to its own materials, is to create "a society that is no longer shaped by the false official account of 9/11."

According to the New York Times, which first reported the story, the programming pushed false narratives about the attacks. The Times reported that the event included "a reference to planted explosives and the view that controlled demolitions, not the planes and resulting fires, were more directly involved in the building collapses."

Speakers included firefighters and survivors of 9/11 victims. One unidentified speaker, per the Times, described the US government's report on the attacks as a "total whitewash."

In a statement to the Times, El Museo del Barrio said: "We sincerely regret this lapse in our vetting process and accept responsibility for the pain this has caused to all of us who continue to endure the tragedy of 9/11. We are currently undertaking a thorough review of our rental policies."

The apology has not quieted criticism. The Anti-Defamation League, a watchdog group focused on antisemitism, raised concerns about the conference — in particular about one speaker who reportedly played a video showing the American and Israeli flags after calling the 9/11 attack a "false flag."

"The so-called 9/11 'truther' movement, once a niche subculture presented with a pseudoscientific veneer, has shifted over time into simplified and sweeping claims about supposed Jewish and Zionist power," the ADL told the Times.

The financial stakes for the museum are considerable. The New York City Department of Cultural Affairs, which is slated to provide more than $1 million in funding to El Museo del Barrio this year, called the event "reprehensible."

Ted Walter, executive director of the International Center for 9/11 Justice, denied that the event was antisemitic or "reprehensible." He accused the Department of Cultural Affairs of attempting to "demean the perspective of so many grieving and hurt New Yorkers who believe that the full truth of 9/11 has yet to be told."

El Museo del Barrio, founded in 1969 and located on Manhattan's Upper East Side, is one of the country's leading institutions devoted to Latinx and Caribbean art. Its statement promises a review of rental policies, but the institution has not said publicly what that review will change, or whether the more than $1 million in city funding remains secure while the controversy unfolds.