Image copyright Reuters Image caption The committee said Mr Blair did not tell other Northern Ireland party leaders about the exact nature of the scheme

The integrity of the criminal justice system has been damaged by the controversial On the Runs scheme, a parliamentary watchdog has said.

The Northern Ireland Affairs committee said the "one-sided, secretive scheme of letters" sent to over 180 Irish republicans should never have existed.

It came to light when one letter caused the Hyde Park bomb trial to collapse.

The On The Runs (OTRs) were republicans suspected of involvement in terrorist crimes but who had never been charged.

The scheme involved the provision of so-called "comfort letters" by the government designed to give them assurances that they were not being sought by police.

One of those who held a letter was John Downey who had been accused of the murders of four soldiers in the IRA Hyde Park bomb in 1982.

The report published on Tuesday said the people of Northern Ireland had been "kept in the dark to the greatest possible extent".

It said the lawfulness of such letters was questionable.

Who are the On The Runs?

Image copyright AP

Anyone already convicted of paramilitary crimes became eligible for early release under the terms of the Northern Ireland Good Friday agreement of 1998.

The agreement did not cover:

• Anyone suspected of, but not charged with, paramilitary offences committed before the Good Friday Agreement.

• Those who had been charged with offences but who had escaped.

• Those who had been convicted of offences but who escaped.

Committee chairman Laurence Robertson, MP, said the scheme had caused "further hurt to people who have suffered far too much already".

He said victims of the Troubles and their relatives had been "let down" by the government.

Media playback is unsupported on your device Media caption Committee chairman, Laurence Robertson MP, says the legal system should be independent of government

"If any scheme had been put in place at all, which is questionable, it should have been properly introduced and correctly administered," he said.

"It also should have been open and transparent. This scheme was none of those things."

Mr Robertson said the government must ensure that no letter provided "a shield from prosecution ever again".

"That is the least people can expect and is the minimum our committee requires," he said.

The government letters were addressed to republican paramilitary suspects, informing them that they were not being sought by the police for questioning about Troubles-related offences.

The Northern Ireland Affairs Committee launched its inquiry after one of the letters resulted in the collapse of the trial of a man charged with four murders.

Image caption The collapse of John Downey's trial led to the On the Runs crisis

John Downey was one of more than 180 republicans who were given letters telling them they were not wanted by the police. But he was wanted by the Metropolitan police

Even though his letter was sent by mistake, a judge ruled that it would be an abuse of process for him to stand trial for the murders of Squadron Quartermaster Corporal Roy Bright, Lieutenant Anthony Daly, Trooper Simon Tipper and Lance Corporal Jeffrey Young on 20 July 1982 in the Hyde Park attack.

The Police Service of Northern Ireland (PSNI) was blamed for what was described as a catastrophic mistake.

Unionists reacted with outrage. First Minister Peter Robinson said the letters were get out of jail free cards. He said they were unlawful and should be rescinded.

Image copyright PA Image caption IRA prisoners on early release emerge through the Maze Prison turnstile in 2000

During its public evidence sessions held in the House of Commons, the Northern Ireland Affairs Committee questioned a number of serving and retired senior politicians.

They included former prime minister Tony Blair, who rejected claims that the letters were unlawful and said the scheme was essential for the success of the peace process.

In its report, the committee said it was questionable whether the OTR scheme was lawful, but said its existence had distorted the legal process.

The report's authors said the integrity of both the criminal justice system and parts of the government had been damaged by the stay on the Downey case.

The committee said no letters should have been sent out by the Northern Ireland Office.

It recommended that all steps should be taken to ensure that OTR letters have no legal effect.

The report said the public had been "deceived" and that transparency was key to public confidence in the fairness of the criminal justice system.

"It is clear the intention was that the people of Northern Ireland and other political parties were kept in the dark about the scheme to the greatest possible extent," it said.

The report said that during the peace process, Sinn Féin had pushed for OTR letters at the highest level and promises had been made by the prime minister.

It said Mr Blair put much effort into ensuring those promises were kept, but did so without telling other Northern Ireland party leaders about the exact nature of the scheme.

The report also accused the Irish government of "trying to persuade HM government to introduce an amnesty for republican terrorist suspects".

It said that if the Police Service of Northern Ireland (PSNI) had known about the entire scheme and had been involved in checking letters sent to OTRs, then "it is almost certain that the Downey judgment could have been prevented".

It also stated that the availability of the scheme to one section of the community "at the whim of one political party" raised questions about equality rules in Northern Ireland.

The report said the PSNI believes 95 of those who hold OTR letters could be linked to nearly 300 murders and that the Metropolitan Police wished to speak to some of them.

It called on the government to provide the resources to enable police to reassess those cases quickly.

PSNI chief constable George Hamilton welcomed the report's acknowledgement that "speeding up the scheme in 2007 made it more difficult for thorough and competent reviews to be carried out and that the PSNI knew nothing about the content of letters sent to suspects until December 2011."

Media playback is unsupported on your device Media caption Theresa Villiers said that the letters are not and never were an amnesty

Speaking to the Northern Ireland Affairs Committee last September, Northern Ireland Secretary Theresa Villiers said the government was no longer standing by the On the Runs letters.

She said those who received letters should no longer rely on them as a defence.

Last July, a separate review into the scheme by Lady Justice Hallet found that it was flawed but not an amnesty for those who received letters.

The judge found the administrative scheme was kept 'below the radar' due to its political sensitivity, but said it would be wrong to characterise the scheme as "secret".