WASHINGTON, United States (AFP) — Republican White House hopeful Donald Trump said Monday that illegal immigrants were bringing “bad genes” into the United States (US), doubling down on previous inflammatory rhetoric about migrants poisoning the blood of the country.

Trump was criticising his Democratic presidential rival Vice President Kamala Harris in a radio interview when he brought up government figures showing there were thousands of immigrants in the United States who were not in federal immigration detention, despite homicide convictions.

“You know now, a murderer — I believe this — it’s in their genes. We’ve got a lot of bad genes in our country right now,” former president Trump told conservative host Hugh Hewitt.

The White House swiftly condemned Trump’s comments as “vile”.

“That type of language is hateful, it’s disgusting, it’s inappropriate, and has no place in our country,” Press Secretary Karine Jean-Pierre told reporters.

“This comes from the same vile statements that we’ve heard about (how) migrants poison the blood, that’s disgusting.”

Jean-Pierre added: “We’re going to continue to forcefully reject this kind of vile, disturbing, hateful, hateful speech.”

Trump was misconstruing data released in September by the Immigration and Customs Enforcement (ICE) agency.

The figures cover a period spanning decades, including when Trump was president, and also don’t include people incarcerated in places other than US Immigration and Customs Enforcement’s (ICE) facilities — in state, local or other federal facilities, for example.

Illegal immigration into the United States, especially over the southern border with Mexico, is a major issue in the November 5 US presidential election.

Polls show it remains a major vulnerability for Harris, with border crossings having risen to record highs at the end of 2023 under President Joe Biden, whom she replaced as the Democratic standard-bearer in July.

But US media reported Monday that migrant apprehensions at the US-Mexico border fell 75 per cent year-on-year in September — to the lowest level since the Trump administration — citing Department of Homeland Security statistics.

Trump, who is neck-and-neck with Harris in nationwide and swing-state polling ahead, has spent much of his campaign demonising both undocumented immigrants and those in the United States legally.

During a rally last month, the 78-year-old former reality TV star said Harris should be prosecuted over Biden’s border policies and called illegal immigrants “animals,” out to “rape, pillage, thieve, plunder and kill”.

“They will walk into your kitchen, they’ll cut your throat,” he said.

And he repeatedly threatened legal Haitian residents in Ohio with deportation, falsely accusing them of eating locals’ pets.

Trump — the oldest major-party White House candidate in history and the first convicted felon to run — accused immigrants of “poisoning the blood of our country” in December in a phrase that earned him comparisons to Adolf Hitler.