It comes after Prime Minister David Cameron announced a judicial review into the controversial scheme on Thursday.Ms Villiers says the coalition government was made aware in 2010 of a list of names "submitted by Sinn Féin to the previous government under an agreement they had reached to clarify the status of so-called on-the-runs".In total, 187 letters were issued to republicans, including 38 since 2010."We will take whatever steps that are necessary to make clear, to all recipients of letters arising from the administrative scheme, in a manner that will satisfy the Courts and public, that any letters issued cannot be relied upon to avoid questioning or prosecution for offences where information or evidence is now or later becomes available," Ms Villiers said on Thursday.The announcement comes after DUP First Minister Peter Robinson gave Westminster an ultimatum - respond to what he branded "a crisis" for Northern Ireland in 24 hours or he would resign.The threat to quit came after revelations sparked by the collapse of the case against Co Donegal man John Downey, who had been charged over the 1982 Hyde Park bomb which killed four soldiers.Mr Downey walked free from the Old Bailey because he was sent a letter by the PSNI wrongly telling him that he was not wanted over any crimes - despite an arrest warrant having being issued by the Metropolitan Police.I should also make it clear that, to my knowledge, this Government did not inform either the First Minister or the Justice Minister of this scheme.Secretary of State Theresa VilliersFollowing the revelations, the DUP leader said that he was not prepared to lead an administration which had been "kept in the dark" by Westminster governments, past and present.Mr Robinson said that he and his party were not aware that the letters had been issued, adding that he would not have entered into power-sharing with Sinn Féin had they known.Ms Villiers says recipients are people who lived outside of the United Kingdom and believed that, if they returned to the jurisdiction, they would be wanted by the police "for questioning in connection with terrorist offences" linked to the Troubles."If it was found that they were not wanted by the police and that there was no prospect of any prosecution based on the evidence then available, the individuals were informed of that fact by letter from a Northern Ireland Office official," she explained."The letters did not amount to immunity, exemption or amnesty from arrest. The letters made this clear."We have always believed in the application of the rule of law and that where the evidential test is met of involvement in terrorism should be subject to due process - whether that person is in possession of a letter or would be eligible for early release under the terms of the Belfast Agreement."Mr Robinson, who had previously called for the full inquiry and for the letters to be rescinded, has welcomed the announcement."The Secretary of State's statement makes it very clear that, if there is evidence or information that requires them to be questioned or if the evidence is there in order to prosecute them, it will go ahead," he said.Mr Robinson added that the get-out-of-jail card "is no longer there".But Sinn Féin deputy First Minister Martin McGuinness has insisted: "Nothing that happened today undermines the status of the letters issued."In taking that stance, he has pointed to remarks by the Attorney General Dominic Grieve stating that the on-the-run cases were handled using what was a "lawful process".