Pat Finucane's son Michael tells Channel 4 News "I don't see why I should accept there was no over-arching conspiracy" as the report into his father's death reveals state collusion on a large scale.

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David Cameron said the report by lawyer Desmond de Silva would make "extremely difficult reading" as it reveals that the army and special branch had advance notice of a series of planned UDA assassinations, but nothing was done.

He said the degree of collusion exposed was "unacceptable" and added in a message to the family: "I am deeply sorry."

Mr Finucane's son Michael told Channel 4 News: "This is a terrible injustice. Successive cover-ups... and an abject refusal to permit a public examination of all of evidence.

"I don't see why I should accept there was no over-arching conspiracy.

"None of the evidence was done in public... the review itself is a broken promise."

Earlier, Mr Finucane's widow Geraldine denounced the report as "a sham... a whitewash... a confidence trick", telling a press conference that "this report is not the truth".

Mrs Finucane added: "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."

The Finucane family claimed they were not included in the de Silva report process and complained that there was a lack of "public scrutiny". Geraldine Finucane has highlighted that the family has "no idea who de Silva spoke to".

More from Channel 4 News: Pat Finucane and Northern Ireland's collusive state
Finucane report findings are a 'broken promise'

Mrs Finucane claimed her family had been "misled and humiliated in a cruel and unnecessary fashion" after they were invited to Downing Street last year only to learn there would be no public inquiry and that instead Mr Cameron was ordering a behind-closed-doors review of documents.

The family also commented that they believe Labour leader Ed Miliband will keep his word and establish an inquiry if there is a future change of government.

The 500-page de Silva report was ordered by the prime minister to investigate security force collusion in his death.

Pat Finucane was shot at his north Belfast home by loyalist paramilitaries from the UDA in February 1989, at the age of 38. He had represented republicans in a number of high-profile cases, but also represented loyalists.

Mr Cameron has previously accepted that collusion took place and apologised but Mr Finucane's widow Geraldine will continue to campaign for a full public inquiry into the murder.

You don't apologise for something but then not fully admit what it is you are apologising for
John Finucane

The review found a "relentless" effort to defeat the course of justice after Mr Finucane's killing and found that army officials provided the Ministry of Defence with highly misleading and inaccurate information.

Mr de Silva found that employees of the state and state agents played "key roles" in the Finucane murder, Mr Cameron revealed, adding: "It cannot be argued that these were rogue agents."

Mr Cameron stated that the army must take a degree of responsibility for targeting activities carried out, with the report revealing that 85 per cent of UDA intelligence in the late 1980s came from security force sources.

He also revealed that Mr Finucane was likely to have been suggested as a target to loyalist paramilitaries by an RUC officer.

Mr Cameron added that he hoped that the report would contribute to moving the peace process forward.

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Family members have been critical of the £1.5m probe, which they say falls short of the full public inquiry they want.

Mr Finucane's son John described the de Silva review as "the embodiment of a broken promise of the British government".

Speaking on BBC Radio 4's Today programme he said: "Every time the government have said they will look into the circumstances of the murder of my father, they have done so in a way which has excluded any involvement of my family.

"Whether that be a police investigation by Sir John Stevens, whether it is a behind-closed-doors, non-statutory review by Desmond de Silva, it prohibits the public - and importantly my family - from having any input, from being able to ask any questions, from being able to see any documents or hear any evidence.

"You don't apologise for something but then not fully admit what it is you are apologising for, and I think that's what the prime minister has done.”

Loyalist paramilitaries shot Mr Finucane 14 times and wounded his wife as they sat eating a Sunday meal at home with their three children.

No public inquiry

Collusion claims were investigated in 1999 by the former head of the Metropolitan Police, Sir John Stevens, whose team charged former Royal Ulster Constabulary special branch agent and loyalist quartermaster William Stobie in relation with the killing.

However, the case collapsed in November 2001 and Stobie was shot dead outside his home weeks later. In September 2004 loyalist Ken Barrett pleaded guilty to murdering Mr Finucane and was sentenced to 22 years in prison.

In 2004 retired Canadian judge Mr Justice Peter Cory was asked to investigate cases of suspected collusion concluding that military and police intelligence knew of the murder plot and failed to intervene, recommending a public inquiry.

Then Northern Ireland Secretary Paul Murphy announced an inquiry under new legislation introduced in 2005 but the Finucane family opposed the Inquiries Act 2005, arguing it would allow government to interfere with the independence of a future inquiry.

Under the new act a government minister could rule whether the inquiry sat in public or private, plans to establish an inquiry were halted by former Northern Ireland Secretary Peter Hain.

The government ruled out a public inquiry into Mr Finucane's murder in October 2011 but put forward a proposal for a leading QC to review the case, which was finally released today.

Pat Finucane's best known client was IRA hunger striker Bobby Sands. He represented a number of hunger strikers during the 1981 Maze prison protest.

He also represented Gervaise McKerr's widow in 1982 after the infamous RUC "shoot to kill incident" and in 1988 he represented Pat McGeown, who faced charges over the so-called corporals killings.