US President Donald Trump has demanded an investigation into what he called "triple sabotage" after an escalator, teleprompter and sound system malfunctioned while he attended the United Nations General Assembly.
The UN said the events that happened while Mr Trump was at its headquarters in New York on Tuesday were accidental and partly blamed the issues on White House staff.
But in a long social media post, the US president described the string of mishaps as "very sinister", called for people to be arrested and said the Secret Service was also probing the events.
In a post on his Truth Social platform, Mr Trump said: "This wasn't a coincidence, this was triple sabotage at the UN. They ought to be ashamed of themselves.
"I'm sending a copy of this letter to the secretary general and I demand an immediate investigation.
"No wonder the United Nations hasn't been able to do the job that they were put in existence to do."
Footage showed the 79-year-old president and First Lady Melania Trump getting on the escalator at UN headquarters on Tuesday before it stopped with a lurch, forcing them to walk up.
Then, as he began his speech, he noted his teleprompter was not working.
He spent much of the rest of the speech criticising the world body, accusing it of funding illegal migration that was turning Western countries into "hell" and failing to support his peace efforts in Gaza and Ukraine.
But while Mr Trump struck a mostly jovial tone about the escalator, his mood hardened a day later.
"A REAL DISGRACE took place at the United Nations yesterday. Not one, not two, but three very sinister events!" he wrote.
Mr Trump said the escalator stop could have been a "real disaster".
"It's amazing that Melania and I didn't fall forward onto the sharp edges of these steel steps, face first," he added.
The president then complained that his teleprompter for his speech was "stone cold dark" for the first 15 minutes and that the sound in the UN auditorium was "completely off".
The US president called for the security tapes for the escalator to be saved, adding: "The Secret Service is involved."
UN spokesperson Stéphane Dujarric on Tuesday issued a statement addressing the matter, saying a videographer from the US delegation "may have inadvertently triggered the safety function" on the escalator.
"Regarding the teleprompter, we have no comment since the teleprompter for the US president is operated by the White House," he said.
A Secret Service official, speaking on condition of anonymity, told AFP the agency was "looking into what the UN said to corroborate it".
Reached for comment after Mr Trump's post yesterday, a UN official, also speaking on condition of anonymity, pointed to Mr Dujarric's earlier statement.
Regarding the alleged sound issues, the official said: "The sound system was designed to allow people at their seats to hear speeches being translated into six different languages through earpieces."
Mike Waltz, the newly installed US ambassador, said on X that he had formally demanded the "complete results" of the UN's probe of the escalator incident, as well as a "detailed explanation of the teleprompter failure's root cause, along with immediate plans to implement robust preventive measures".
"The United States will not tolerate threats to our security or dignity at international forums," Mr Waltz said.
"We expect swift cooperation and decisive action," he added.
