Republican presidential candidate Donald Trump called President Barack Obama and Democratic candidate Hillary Clinton "co-founders" of DAESH, in remarks certain to ignite fresh criticism of his campaign style.

Republican US presidential nominee Donald Trump attends a campaign rally at the BB&T Center in Sunrise, Florida on August 10, 2016.
Republican US presidential nominee Donald Trump attends a campaign rally at the BB&T Center in Sunrise, Florida on August 10, 2016.

Republican candidate Donald Trump has dropped another bombshell on the US presidential race, with the jaw-dropping assertion that President Barack Obama and Democratic candidate Hillary Clinton "founded" the DAESH terrorist organisation.

Addressing supporters at a rally in Fort Lauderdale, Florida, the real estate tycoon said the terrorist group is "honouring President Obama."

"He is the founder of ISIS [DAESH]," Trump said.

"He's the founder of ISIS [DAESH], okay?" he added. "He's the founder! He founded ISIS [DAESH]."

"And I would say, the co-founder would be 'Crooked Hillary Clinton'," Trump shouted, over cheers and applause from the crowd.

The New York real estate developer has previously criticised Obama and Clinton, secretary of state from 2009-13, for how the United States pulled out of Iraq after the war, saying it helped create the terrorist group that has seized swaths of Iraq and Syria.

The idea that a sitting US president created a terrorist group determined to kill Americans and other Westerners took that criticism to a new level. Trump first made the assertion in a speech on Wednesday night in Florida. He repeated it in an interview on Thursday morning with CNBC.

"He [Obama] was the founder of ISIS [DAESH]. And so was she. I mean I call them co-founders," said Trump, who says he opposed the Iraq war.

"He shouldn't have gotten out way he got out. It was a disaster, what he did," he told CNBC.

Clinton spokesman Jesse Lehrich, in response to Trump's comments, pointed to US advances against the terrorist group in Libya this week. "FYI - US-backed militias retook ISIS's [DAESH's] stronghold in Libya today thanks to Obama-authorised air strikes," he said in a tweet late on Wednesday.

Trump did not back down, asking on CNBC: "Is there something wrong with saying that? Why - are people complaining that I said he was the founder of ISIS [DAESH]? All I do is tell the truth, I'm a truth teller."

Supporters of Trump, who has never held elected office, like his combative and often insulting style, which has drawn wide criticism, including from some in his party. He has said that if that style costs him the election in 90 days, he will go back to a good life.

"It's not what I'm looking to do - I think we're going to have a victory but we'll see," he said.

In a wide-ranging interview, Trump also said the United States will continue engaging in free trade if he is elected.

"We are absolutely going to keep trading. I am not an isolationist ... I'm a fair trader," Trump said.

Growing list of disquieting statements

Trump appeared to suggest on Tuesday, possibly in jest, that Clinton or her Supreme Court nominees could be shot, as a way of preventing her from making judicial appointments if she wins the November presidential election.

The former secretary of State on Wednesday sternly rebuked her Republican presidential rival's "casual inciting" of violence, saying he had "crossed the line."

"Yesterday we witnessed the latest in a long line of casual comments by Donald Trump that crossed the line," Clinton told a rally in Des Moines, Iowa.

"Words matter, my friends. And if you are running to be president, or you are president of the United States, words can have tremendous consequences."

Trump and his campaign quickly sought to douse these flames, insisting the Republican flag bearer was merely urging gun rights supporters to reject her candidacy at the ballot box.

Clinton also warned of the dangers of reckless language during a presidential race.

She slammed Trump's "casual cruelty to a Gold Star family," referring to the billionaire's clash with the parents of a Muslim American soldier who was killed in action.

"His casual suggestion that more countries should have nuclear weapons, and now his casual inciting of violence," she added.

"Every single one of these incidents shows us that Donald Trump simply does not have the temperament to be president and commander in chief of the United States."

Source: TRTWorld and agencies