The Chief Constable of West Yorkshire Police has apologised for any upset caused by his statement that Liverpool fans' behaviour made policing at the Hillsborough tragedy "harder than it needed to be".
Sir Norman Bettison said his role was never to "besmirch" the fans and said the Reds' supporters were in no way to blame for the disaster.
The chief constable said he was "deeply sorry that impression and slight has lingered for 23 years".
In a statement released this afternoon, Sir Norman said: "Let me speak very clearly. The fans of Liverpool Football Club were in no way to blame for the disaster that unfolded at Hillsborough on 15 April 1989.
"I formed this clear view on hearing all the evidence that was presented at the Taylor inquiry, having sat through every day from its beginning, just four weeks after the tragedy, through to its conclusion.
"The evidence was overwhelming. The police failed to control the situation, which ultimately led to the tragic deaths of 96 entirely innocent people.
"I can be no plainer than that and I am sorry if my earlier statement, intended to convey the same message, has caused any further upset.
"My role was never to besmirch the fans. I did not do that.
"I am deeply sorry that impression and slight has lingered for 23 years."
Sir Norman was an off-duty South Yorkshire Police inspector when he attended the game and was involved in an internal inquiry held by the force in its aftermath.
Yesterday, he denied any wrongdoing but sparked fury with his comments, which led to calls for him to resign.
Asked by ITV News earlier today if he was part of a "black operations unit" to smear the fans, Sir Norman said: "No not at all, there wasn't a black ops unit. I wasn't part of it. I was part of a team trying to put together the facts in a concentrated time period for my chief constable."
Earlier today, Deputy Prime Minister Nick Clegg told the BBC he could see why people were "livid" about Sir Norman's previous statement.
"I think his comments were ill-judged and insensitive," the Liberal Democrat leader said.
"If I was a family on Liverpool, Merseyside, of someone who died on that day, I would be livid."
The damning Hillsborough Independent Panel report revealed a cover-up took place to shift the blame on to the victims and that 41 of the 96 lives lost at Sheffield Wednesday's Hillsborough stadium on April 15, 1989, could have been saved.
The panel found 164 police statements were altered, 116 of them to remove or alter "unfavourable" comments about the policing of the match and the unfolding disaster.
Reviews have been ordered by police authorities in West Yorkshire, into the actions of Sir Norman, and West Midlands, which also conducted an investigation into the disaster.
South Yorkshire Police, which still employs 195 officers who were on duty at the ground on the day of the tragedy, said the force would refer itself to police watchdog the Independent Police Complaints Commission.
Earlier today, chief constable David Crompton said South Yorkshire Police would consider asking the IPCC whether those involved in the Hillsborough tragedy should face manslaughter investigations.
Mr Crompton said the force was looking into a number of issues to refer to the watchdog, including corporate manslaughter, manslaughter and misconduct in public office.
Mr Crompton told a South Yorkshire Police Authority meeting in Barnsley: "Clearly, there may be potential for corporate manslaughter, given some of the detail which came out the other day. That relates, of course, to how things were handled on the day and the view taken about the 3.15 cut-off point.
"In addition to that, there may, again potentially, be the possibility of manslaughter investigations against individuals."
He added: "In relation to alteration of statements, which has received a great deal of publicity this week, clearly, that is something that we are looking very closely at. It's highly likely that that will form part of the referral to the IPCC."
Mr Crompton continued: "The other areas that we will be considering referring to the IPCC will be issues of misconduct in public office, also leaking information to the media, issues to do with the data protection act in relation to some of the checks that were done on the PNC.
"I do wish to make it absolutely clear that, although we haven't worked out the full details yet, there will be a referral to the IPCC in the next couple of weeks. That is not in any doubt."
Trevor Hicks, from Keighley, West Yorkshire, who lost daughters Vicky, 15, and Sarah, 19, in the tragedy, said the families would not speculate on what charges should be brought before they had reviewed the evidence.
He said: "David Crompton is the first chief constable who has ever actually done anything about Hillsborough and we commend him for it and we thank him for it.
"Our view is that if criminal actions have taken place then criminal charges should follow.
"Exactly what those criminal charges should be is a matter we will look into when we review the evidence."
Mr Hicks added: "We've been let down by the state but we didn't give up for 23 years and you can be sure, now we have been vindicated, that we will ensure that this time the state does the right thing.
"This goes beyond Hillsborough, it's about the public having confidence in the police and other authorities.
"This has to be cleaned up and society needs to see it has been cleaned up and we will ensure it is cleaned up, no matter how long it takes.
"We will catch up with the villains, no question about that."
Mr Hicks said many of the families were "only just beginning" to start looking at the 400,000 documents now the enormity of Wednesday's disclosures was sinking in.
They are due to meet as a group on Sunday to discuss where they go from here, he said.