Speaking on Fox News Saturday, Senator Rand Paul demanded that an investigation be started into where money given to groups such as Black Lives Matter is being spent, and if it is being used to spark violence in major US cities.

"The question is, who is financing this and who is flying them around?" Paul asked.

"It really is a federal crime to incite riot and to fly people around to instigate violence. And I think that's what's happening," the Senator urged.

"And yes, we've got to get to the bottom of this one person at a time, and once we have suspicion or probable cause, we need to ask a judge for a warrant and they need to look at their financial records and see — for this," he added.

When asked if he had an idea of who was financing these groups, Paul said "there's one or two possibilities."

"It could be nefarious rich individuals who want to foment violence in our cities, or it could be less sinister but still equally as bad," the Senator explained.

"Black Lives Matter is out there collecting corporation money from corporations who want to show the public that they're not racist. But these corporations need to know if that money is going to Black Lives Matter and if Black Lives Matter is giving it to hooligans to cause and create havoc in cities," Paul emphasised.

"Someone has to trace the money. I don't know the answer yet. But I certainly think we need to know," he added.