US police investigating if Donald Trump `incited riot`

North Carolina authorities said Monday they are looking into whether Republican presidential frontrunner Donald Trump incited a riot at a rally where a black protester was punched in the face by a supporter.

It comes after a weekend of violent clashes and protests at Trump events and ahead of "Super Tuesday 2," with Democratic and Republican primary contests in the states of Florida, Illinois, Missouri, North Carolina and Ohio.

John McGraw, 78, was charged with assault, battery and disorderly conduct after sucker-punching Rakeem Jones at a chaotic Trump rally on Wednesday in Fayetteville, North Carolina.

Trump said over the weekend that he was considering paying McGraw`s legal fees.

Police are now delving into whether Trump, who is accused by critics of fueling the increasingly toxic atmosphere surrounding his rallies and the wider campaign, also broke the law that night.

"We are continuing to look at the totality of these circumstances, including any additional charges against Mr McGraw, including the potential of whether there was conduct on the part of Mr Trump or the Trump campaign which rose to the level of inciting a riot, and including the actions or inactions of our deputies," the Cumberland County Sheriff`s Office said in a statement.

McGraw, who later said that next time "we might have to kill" Jones, is due in court on April 6.

Clashes erupted at a Trump rally in Chicago on Friday, marking an escalation in the tensions that have trailed the bombastic Republican candidate, who has called Mexicans rapists and urged a ban on Muslims entering the US.

Protesters turned up at a rally staged by the 69-year-old billionaire in Hickory, North Carolina again Monday, but this time, he patiently waited for their chants to subside.