Edits made to the Hillsborough disaster page on Wikipedia have been described as an "absolute insult to victims and their families".
Margaret Aspinall, mother of one of the victims said: "It's an absolute insult to the families who are fighting for where we are today and it has to be investigated".
Sheila Coleman from the Hillsborough Justice Campaign added that the distress was compounded by the timing of the revelations.
"That this happens now when the families are immersed in the inquest procedure goes to the heart of why should they trust the establishment," she said.
More top news
It'll become increasing cloudy tonight, with outbreaks of rain in the northwest
Six months on from the referendum, Political Editor Robert Peston takes a road trip to find out what people feel about Brexit now.
Donald Trump has been criticised for appointing a man who once sued the Environmental Protection Agency to be its new boss.