Theresa Villiers said she has resigned as Northern Ireland Secretary, adding that the "new Prime Minister was kind enough to offer me a role but it was not one which I felt I could take on".
Northern Ireland Secretary Theresa Villiers has said that individuals with so-called 'letters of comfort' would be treated by the authorities in exactly the same way as individuals who did not have one.
Ms Villiers said she would make a fuller written statement to Parliament in "the coming days".
The Northern Ireland Secretary has said that republicans suspected of crimes committed during the Troubles should "no longer draw comfort" from letters informing them that police were no longer pursuing them.
Theresa Villiers told a Westminster committee that she had to clarify the status of the so-called 'letters of comfort' after a judge-led review called their accuracy into question.
The issue came to light in February when the case against a man accused of the 1982 Hyde Park bombing collapsed because it emerged he had been sent one of the letters in error.
In July, an inquiry found that the letters were flawed and "did not amount to an amnesty" for terror suspects.
In a speech today, Northern Ireland Secretary Theresa Villiers is expected to call for a focus on paramilitaries rather than the police as part of future measures to heal divisions over the conflict. She is expected to say:
The Northern Ireland Secretary is to call for "proportionate" focus on wrongdoing by republicans and loyalists rather than the police as part of future measures to heal divisions over the conflict.
Many processes for addressing the legacy of the past - during which thousands were killed or maimed amid 30 years of bombings and shootings - have concentrated on the activities of security forces, Theresa Villiers will argue, rather than paramilitaries who were responsible for most cases.
The devolved ministerial Executive at Stormont is spending more than £30 million a year on historical matters, with police trawling hundreds of thousands of documents, in part to investigate shootings carried out by former officers or soldiers.
Northern Ireland Secretary Theresa Villiers has condemned an attempted letter bomb attack after a viable device was found at a postal sorting office in Londonderry.
Ms Villiers said, "Once again these individuals have demonstrated a completed disregard for our postal workers and the local community. Anyone with any information should pass it to PSNI [Police Service Northern Ireland]."
Stormont's Deputy First Minister will hold talks with the Northern Ireland Secretary as a political crisis triggered by the collapse of the Hyde Park bombing case continues to threaten the future of the devolved administration in Belfast.
Sinn Fein's Martin McGuinness and Theresa Villiers are set to meet at Stormont Castle to discuss the controversy that prompted First Minister Peter Robinson to threaten to resign.
The Democratic Unionist leader has effectively given the UK Government 24 hours to respond to his demand for a public inquiry into secret letters sent to IRA suspects that assured them they would not be prosecuted.
Northern Ireland Secretary Theresa Villiers has appealed for calm ahead of a controversial parade commemorating deceased IRA members.
Ms Villiers said: “I know the deep pain this parade will cause the families of victims in West Tyrone and the rest of Northern Ireland.
“I would appeal for calm in Castlederg today.
“All possible support must be given to the police in upholding the rule of law and acting to keep the community safe at this tense time.”
Northern Ireland Secretary Theresa Villiers called last night's violence in Belfast "shameful" after 26 police officers were injured.
Ms Villers continued, "After success for Northern Ireland this summer as host to both the G8 and the World Police and Fire Games, disorder on the streets is a hugely regrettable step backwards.”