The Ukip leader, who is fighting the Stoke-on-Trent by-election, responded to allegations that he has lied about his attendance at the 1989 FA cup semi final.
Nuttall, who was 12 at the time of the tragedy and at school in Bootle, Merseyside, first publicly claimed he was at Hillsborough in a letter to a local newspaper in 2010.
He has since shared his account with the BBC and the Sunday Express newspaper.
“We were in the upper tier at the Leppings Lane end and that is where people were being pulled out,” he told the Sunday Express last week.
“So it was all happening below us and we were in the crush outside before and we got through the turnstile.”
An inquest ruled last year that 96 fans were unlawfully killed at Hillsborough, one of the worst sporting disasters in living memory.
However, questions over Nuttall’s account have been raised by a prominent Hillsborough campaigner.
Margaret Aspinall, whose son died during the disaster, was quoted in the Guardian on Friday as saying: “I haven’t heard anything about him being at the match.
“Has he given a statement to the police, who have said they want to hear from everyone who was there?
“He can’t say he hasn’t heard that the police want to take statements from everyone who was in the Leppings Lane, as it’s been all over local and national media.”
The Guardian reported that Ukip sent statements from Nuttall’s father and another person to corroborate the leader’s account.
In a statement sent to The Huffington Post UK, Ukip said the claims were part of a “smear campaign” sanctioned by senior Labour figures. The full statement said:
“Paul has been aware for some time of a smear campaign against him sanctioned by senior figures in the Labour Party and spoke about this in an interview with the Sunday Express last week.
“One aspect of this is the claim that he was not at the Hillsborough disaster. This is totally false and highly defamatory.
“Paul was indeed at Hillsborough. He attended the match with his father and other family members.
“For political opponents to suggest otherwise and for left-wing media organisations to promote such claims constitutes a new low for the Labour Party and it’s associates. (sic)
“Paul will not allow such disgusting attacks, which have already caused great distress to his family, to deflect him from his campaign to be elected MP for Stoke-on-Trent Central.
“[He] trusts that the people of Stoke and the British public in general will share in his disgust that the Labour Party should sink to such a level.”
HuffPost UK did not receive separate statements from Nuttall’s father or the other person, as reported by the Guardian.
HuffPost UK has contacted the Labour Party for comment.