Indianola, Iowa - Several young protesters called Donald Trump a "climate criminal" as they briefly disrupted an Iowa campaign event by the former president on the eve of the state's first-in-nation vote in the Republican presidential nomination race.

One protester held a black-and-yellow banner bearing the same three words before being quickly hustled from the room by guards, in an incident witnessed by AFP journalists.

The roomful of Donald Trump supporters at Simpson College in Indianola responded with loud shouts of "USA, USA!"

Trump, the frontrunner for the 2024 Republican nomination, called one of the protesters "young and immature" as she was being escorted out.

Marjorie Taylor Greene Marjorie Taylor Greene repeats claim that Democrats are "pedophiles" over Biden's clemency grant

"They're fighting oil," he said. "They're basically saying let's close up on our country."

Trump, who holds an overwhelming lead in polls ahead of Monday's Republican presidential caucuses in Iowa, has long questioned the scientific consensus that human activities are a major contributor to global warming.

As president, one of his first acts was to withdraw the US from the 2015 Paris climate agreement, and he has vowed, if re-elected, to vigorously promote the production of fossil fuels.

As Trump and much of the Republican Party continue to deny the reality of climate change, an extreme cold front gripping large parts of the country – including Iowa – has been linked to the effects of an increasingly unstable environment.