Pat Finucane, a solicitor in Belfast who had represented clients including convicted members of the IRA, was murdered by loyalist gunmen at his home in 1989.
The government-ordered review, by Sir Desmond de Silva, found that, while there were "shocking levels of state collusion" in facilitating the killing, there was no "overarching state conspiracy".
Mr Finucane's family have long called for a full public inquiry into the murder but Prime Minister David Cameron has ruled that out.
Here are some reactions to the review:
"At every turn, dead witnesses have been blamed and defunct agencies found wanting. Serving personnel and active state departments appear to have been excused.
"The dirt has been swept under the carpet without any serious attempt to lift the lid on what really happened to Pat and so many others.
"This report is a sham, this report is a whitewash, this report is a confidence trick dressed up as independent scrutiny and given invisible clothes of reliability.
"But most of all, most hurtful and insulting of all, this report is not the truth."
"David Cameron today sought to use the review as a pretext for denying the family a public inquiry - a commitment that was made by the British government at Weston Park in 2001.
"This is not acceptable to the family or to Sinn Fein and it should not be acceptable to the government here.
"The information provided by Desmond de Silva is a damning indictment of British state collusion in the murder of citizens.
"It reveals some of the extent to which this existed. It does not diminish the need for a public inquiry.
"On the contrary, it makes such an inquiry more necessary than ever."
"There is more than a shred of evidence that the Republic of Ireland's government armed the Provisional IRA and there should be an investigation into that and honesty about that, so as we see all of the picture.
"My constituents are sick and tired of a one-sided narrative of revisionism that says the Provisional IRA were actually quite good and the troops and the police were actually quite bad."
"I want to say clearly that I was very proud to stand with the Finucane family in those desperate times at Pat's funeral as they buried Pat.
"The SDLP and I will stand with them today, and indeed into the future, because we support their demand for a full public inquiry.
"We feel that we have still only got half the truth out here. There are people out there who should be held to account even though it is 23 years too late."
"Given the number of security forces personnel involved, the 24/7 threat - not only to their lives but those of their families, neighbours and anyone who happened to be in their vicinity - and given the length of the terror campaign against them, it was inevitable that decisions were made which, on occasions, appear differently with the benefit of historical hindsight.
"Indeed, the IRA and republican movement often created the conditions which maximised the likelihood of such circumstances. This is part of the definition of the impact of terrorism."
"I am deeply sorry and, on behalf of the police service, I offer a complete, absolute and unconditional apology to Mr Finucane's wife, Geraldine.
"I know that the vast majority of colleagues, both past and present, will share in my profound sadness and disappointment at how the Finucane family were so badly and abjectly failed.
"This failure has done a great disservice to the bravery and dedication of the many who joined the police to keep all communities safe throughout the awfulness of those difficult times."
"The collusion demonstrated beyond any doubt by Sir Desmond - which included the involvement of state agents in murder - is totally unacceptable.
"We do not defend our security forces - or the many who have served in them with great distinction - by trying to claim otherwise.
"Collusion should never, ever happen. So on behalf of the government and the whole country, let me say once again to the Finucane family, I am deeply sorry."
"This report is incredibly frank. It has hugely harsh things to say about what went on with the involvement of state agents in murder.
"It's something which is profoundly shocking and I simply don't believe that a public inquiry would take this further.
"This report has revealed the facts about what happened and I don't believe that waiting 10, or even 12 years, for a public inquiry to complete would reveal more facts about Pat Finucane."
"There was a very strict Army instruction that they were not to get involved in anything illegal - they quite clearly did.
"There was quite clearly a breach of the instructions at the time and that's the seriousness of it.
"He added: "This has revealed a very serious situation in this case. What is so serious about it is that is impugns the RUC and the UDR and the British intelligence, security and British Army when, in fact, the majority of the people involved were extremely brave."
"We must, as the United Kingdom, accept that our state sometimes did not meet the high standards we set ourselves through the Northern Ireland conflict.
"Anyone reading this report will believe it is an appalling episode in our history.
"All sides of the House believe that we must establish the full and tested truth about Pat Finucane's murder but, on this side of the House, we continue to believe that a public inquiry is necessary for his family and Northern Ireland."
"A public inquiry would be able to compel witnesses to come to it; you'd have to have people giving evidence in public to that inquiry.
"You'd be able to test what they were saying, you'd be able to review the evidence of one against another - it's the confidence that it then gives to people.
"They can see justice being done and justice being seen to be done is especially important in cases such as this."
"The fact that the Force Research Unit (military intelligence), the special branch, were operating in this freewheeling way illegally, using their own agents to commit and be involved in the committal of murders is a shocking stain on Britain's involvement in Northern Ireland.
"Yes, it was difficult - the IRA were committing enormous atrocities, the Ulster Volunteer Force, the Ulster Defence Association, other paramilitaries were committing terrible atrocities and acts of terrorism.
"But that does not excuse state collusion in murder which is what happened to a respected Belfast solicitor."
"I have spoken today with Geraldine Finucane and I know that the family are not satisfied with today's outcome.
"I intend to reflect carefully over the coming days on the detailed content of the De Silva report, and indeed previous reports, as well as the prime minister's statement today.
"I also intend to consult further with the Finucane family to hear their views and concerns in more detail."
"The reality is that the Finucane family were an IRA family and I can illustrate that by saying that, when I gave that allegation publicly and was being sued for libel, the family retracted and paid my legal expenses.
"So let's not fool ourselves about the godfather Finucane, who was killed.
"If there was connivance then let me say we talk, all of us who served through the heart of the Troubles of Northern Ireland, we served in a way where it was impossible to have secrets.
"Why were there 10 attempts on my life? Why was Lord Kilclooney shot? Because there was conspiracy. Less than 1% of all terrorist suspects involved in proactive security force operations were killed by the security forces, 99% ended in arrest."
Britain's security services colluded in one of the most notorious killings during the Troubles in Northern Ireland, an official report has concluded.