Leaders in the US state of Ohio are trying to douse baseless rumours that Haitian immigrants in a town there have been eating residents' pets as food.

The allegations have percolated up through right-wing media and were amplified by Donald Trump at his presidential debate with Kamala Harris on Tuesday.

"This is something that came up on the internet, and the internet can be quite crazy sometimes," Ohio Governor Mike DeWine said.

On Tuesday, a parent in the town of Springfield accused Republicans of politically exploiting his son's death in a crash caused by a Haitian migrant.

Authorities say some 15,000 migrants of Haitian origin have resettled over the past couple of years in Springfield, a south-western Ohio town with a population of less than 60,000 people.

Some local residents have expressed frustration over the influx, saying the newcomers are straining city resources, from housing to healthcare.

In recent weeks unsubstantiated claims have surfaced on social media that the migrants are abducting and eating animals, from pet cats and dogs to park ducks.

Trump, his running mate JD Vance, the world's richest man Elon Musk and other conservatives have amplified the reports.

But Springfield Mayor Rob Rue said on Tuesday that "we have not been able to verify any credible reports or specific claims of pets being harmed, injured or abused by individuals within the immigrant community".

"The news story regarding a cat being killed or consumed did not originate in Springfield," he added. "It actually involved a Canton woman who was arrested for animal cruelty last month."

Canton is an Ohio city north-east of Springfield.

"I think we go with what the mayor says," Governor DeWine told CBS on Wednesday. "He knows his city."

A moderate Republican who has endorsed Trump's re-election bid, DeWine has pledged to invest in Springfield's healthcare and education systems to address its "unprecedented" population increase, but he also defended the newcomers.

"These Haitians came in here to work because there were jobs, and they filled a lot of jobs. And if you talk to employers, they've done a very, very good job and they work very, very hard," he said.

On Thursday Springfield officials evacuated city hall following reports of a bomb threat. It is not yet known whether the incident was connected to the immigration controversy.

Last year a Haitian immigrant driving without a valid US licence crashed his minivan into a school bus in the town.

One student - Aiden Clark, 11 - died after being thrown from the bus as it flipped, while 20 others were sent to the hospital.

The driver, Hermanio Joseph, was found guilty of involuntary manslaughter and felony vehicular homicide, and sentenced to nine to 13-and-a-half years in prison.

On Monday, the Trump campaign's X account posted side-by-side photos of Aiden and Joseph, and attacked Vice-President Harris' immigration policies before the presidential debate.

At a city commission meeting the next day, Aiden's father, Nathan, said he wished his child had been killed "by a 60-year-old white man" so "the incessant group of hate-spewing people would leave us alone".

The Trump campaign told the BBC it was "deeply sorry to the Clark family for the loss of their son".

"We hope the media will continue to cover the stories of the very real suffering and tragedies experienced by the people of Springfield, Ohio, due to the influx of illegal Haitian immigrants in their community," the campaign said.

Just a few hours after Mr Clark spoke, Trump repeated the claims about Haitian immigrants eating pets in a TV debate watched by more than 67 million viewers.