The United Nations told President Donald Trump it had launched a "thorough investigation" into what the US leader called "triple sabotage" during his visit to the organization's headquarters.

The US sent a letter to the UN Secretary-General Antonio Guterres on Wednesday demanding answers about an escalator that failed, stranding Trump and first lady Melania Trump, as well as a malfunctioning teleprompter and a faulty public address system.

"The Secretary-General informed the US Permanent Mission that he had already ordered a thorough investigation, and he conveyed that the UN is ready to cooperate in full transparency with relevant US authorities on this matter to determine what caused the incidents referred to by the United States," Guterres's spokesman, Stephane Dujarric, said late Wednesday.

In a long, angry social media post, Trump described the string of mishaps as "very sinister," called for people to be arrested and said the US Secret Service was also conducting a probe.

"This wasn't a coincidence, this was triple sabotage at the UN. They ought to be ashamed of themselves," Trump said on his Truth Social platform.

"I demand an immediate investigation," he said.

He was dogged by technical gremlins before and during his keynote speech to the organization and world leaders gathered at the UN General Assembly hall in New York.

Footage showed the 79-year-old president and Melania Trump getting on the escalator at UN headquarters on Tuesday before it stopped with a lurch, forcing them to walk up.

Then later, as he began his speech, he noted his teleprompter was not working.

He spent much of the rest of the speech bashing the world body, accusing it of funding illegal migration that was turning the United States and European countries into "hell" and failing to support his peace efforts in Gaza and Ukraine.

While Trump struck a mostly joking tone about the escalator, his mood hardened a day later.

The UN has gently insisted that the teleprompter was operated by the White House.

As for the escalator, Dujarric, the secretary-general's spokesman, issued a note to reporters Wednesday saying that a videographer with the US delegation, who was filming on the escalator ahead of the first US couple, accidentally tripped a switch that caused the moving staircase to stop.

Trump also complained the public address system had been rigged so that his hour-long speech could not be heard.

"The sound system was designed to allow people at their seats to hear speeches being translated into six different languages through earpieces," said a UN official speaking on condition of anonymity.