Farage, who was an MEP from 1999 until 2020, and was UKIP leader from 2006 to 2009 and 2010 to 2016, was also questioned about his former UKIP MEP colleague Nathan Gill, who was jailed for ten and a half years last Friday after admitting taking bribes to make pro-Russian interviews and statements when he was an MEP.
Gill was first elected to Brussels as a UKIP MEP in 2014, becoming a Brexit Party MEP in 2019, sticking with the party when it became Reform UK, and becoming Welsh leader in 2021, although he failed to get re-elected shortly afterwards.
Speaking at a Reform UK rally in Llandudno, north Wales, Farage said Gill was "briefly… leader of Reform Wales".
The fact Gill took bribes "is of course an absolute and total disgrace," he said.
"We disown his actions and we disown what he has done in every single way."
In a separate interview, Farage was asked if he needed to investigate any other Russian links within his party, but said: "I'm not a police force, I haven't got the resources."
He added he thought there should be a broader investigation into Russian and Chinese interference in British politics, suggesting MI5 should conduct it.
Farage said he was as confident "as I can be" that no one else in Reform past or present had done similar things to the former Reform Wales leader, labelling the issue a "very minor embarrassment for Reform".
He said: "I'm very shocked about Gill – he was in UKIP for a very, very long time – albeit it his time in Reform was very, very short...
"I've had no engagement with him and nobody in my leadership team has had any engagement with him whatsoever."
Asked if that meant he could not rule out that there might be people in the party that might have spoken to him since his arrest, he added: "Nobody in authority."
Responding to the accusations of racism during Farage's schooldays, Liberal Democrat President-Elect Josh Babarinde MP said: "The Reform leader's refusal to deny that he's said these racist remarks is unbecoming from someone who wants to be our next prime minister.
"The British people deserve a straight answer.
"It looks like the mask has slipped and fact-of-the matter-Farage is turning into no-answers-Nigel."
And Labour accused Nigel Farage of claiming "you can racially abuse people without it being hurtful and insulting".
Lord Mike Katz, a Labour peer and former Chair of the Jewish Labour Movement, called on Farage to "come clean" about the claims and said "failure to do so would be yet more evidence that Farage is simply unfit for office".
He said: "Just when you thought Nigel Farage couldn't sink any lower, he is trying to say abhorrent racist comments, including vile antisemitic insults, doesn't matter.
"He seems to think that you can racially abuse people without it being hurtful and insulting. Let's be crystal clear: you can't."