A man set himself ablaze Friday outside the court where Donald Trump is standing trial, throwing pamphlets that police said contained conspiracy theories before he was taken to a hospital in critical condition.

Police named the man as Maxwell Azzarello from St Augustine, Florida and said the pamphlets he sought to disseminate "seem to be propaganda-based."

"(They were) almost like a conspiracy theory type of pamphlet, some information in regards to Ponzi schemes, and the fact that some of our local educational institutes are a front for the mob," NYPD chief of detectives Joseph Kenny told reporters.

"His condition is not good, but as of now he is still alive."

Deputy police commissioner Tarik Sheppard said "we just right now labelled (him) a sort of conspiracy theorist, and we're going from there."

Burning clothes were strewn in the park, which was locked down by authorities, while ambulances lined up nearby on standby, an AFP correspondent at the scene saw, describing a strong smell of burning chemicals.

Laura Kavanagh, the New York City fire commissioner, said four officers were lightly injured in the incident. She described Azzarello's condition as "critical."

Video seemingly taken by witnesses and posted on social media showed a person standing engulfed in flames, then falling to the ground as police officers, including one with a fire extinguisher, rushed to beat out the blaze.

https://www.youtube.com/watch?v=3f0h_pprZoc

- Tight security -

A witness who gave his name as Dave, 73, told AFP he saw a man throwing pamphlets before dousing himself with an unspecified liquid and lighting himself on fire.

TV reporters described the incident unfolding moments after the full panel of 12 jurors and six alternates was selected for the trial of the former president in a hush money cover-up case.

A CNN reporter described a heavy stench of burning flesh in the aftermath of the blaze.

Hearings in the case resumed after lunch despite the incident. Trump declined to respond to questions about Azzarello as he returned to court after the break.

The self-immolation happened in a park opposite the 100 Centre Street courthouse, which has been used by authorities to corral protesters, both pro-Trump and anti-Trump, as well as well as by some members of the media.

Officers said they had swept the area and found no incendiary devices.

Trump's criminal trial, the first of a former president, is being conducted amid tight security in a 15th floor courtroom swarming with Secret Service officers as well as court police.