Ukip leader Paul Nuttall has said he is "very sorry" over a false claim that he had lost close personal friends in the Hillsborough disaster.
Mr Nuttall was forced to admit the claim posted on his website was wrong after he was challenged during an interview with Radio City Talk in Liverpool.
"I haven't lost a close personal friend, I've lost someone who I know," he told presenter Dave Eason, adding: "I haven't put that out, that is wrong."
In a statement later, Mr Nuttall said he was "appalled" when he found out what had happened but he did not write the web posting.
"This was an article that I did not write and did not see prior to it being posted by a member of my staff," he said.
"Of course I take responsibility for those things that are put out under my name, but I was genuinely taken aback when this claim was brought to my attention and am both appalled and very sorry that an impression was given that was not accurate."
Lynda Roughley, a press officer for Mr Nuttall, subsequently said she had offered to resign, saying she had been "entirely responsible" for the website post.
"I am frankly mortified at the distress this issue has caused Paul and may have caused to anyone involved with the Hillsborough tragedy," she said in a statement. "I could not be more sorry."
In an entry on the website dated August 2011, Mr Nuttall called for the government to release files it held on the 1989 Hillsborough disaster.
He was then quoted as saying: "Without them being made public we will never get to the bottom of that appalling tragedy when 96 Liverpool fans including close personal friends of mine lost their lives."
Mr Nuttall, who is now standing for Ukip in the Stoke-on-Trent Central by-election, has previously hit out over an article in The Guardian which cast doubt on his claim that as a 12-year-old fan he was present in the stadium when the disaster happened.
In his Radio City Talk interview, he compared his treatment by the paper to The Sun's coverage of the disaster which wrongly claimed drunken Liverpool fans were to blame.
"What's happening to me now, in many ways, is a national newspaper doing precisely what happened to the people there on the day," he said.
"When The Sun told those lies, I've now got The Guardian doing precisely the same to me."
The paper quoted two people who knew him, a childhood friend and a former teacher, who could not recall Mr Nuttall ever mentioning he had been at the stadium.
The disclosure of the claim he lost friends in the disaster has angered some among the Hillsborough families.
Barry Devonside, whose son Christopher, 18, was among the victims, said the Ukip leader's credibility had "gone out of the window".
"It's insensitive. We are still awaiting the decision of the Crown Prosecution Service as to whether charges will be brought and we don't need this kind of thing from Paul Nuttall," he said.
"He should know better as a politician and leader of Ukip."
Hillsborough Family Support Group chairwoman Margaret Aspinall told LBC radio: "A lot of people who were there that day did lose close personal friends and I think it's an insult to them as well as to all the families who did lose somebody on that day."
In his statement, Mr Nuttall made clear he stood by his claim to have been at the match.
"From the upper tier of the Leppings Lane End of the Hillsborough Stadium, I watched the events of that day unfold with horror," he said.