Media playback is unsupported on your device Media caption Peter Robinson: "I'm satisfied with the response that I've got... I do not intend to resign"

First Minister Peter Robinson has welcomed the inquiry set up to look into the NI secret letters row.

Mr Robinson also said he was happy with the terms of reference for the inquiry.

He had threatened to resign over the issue of On the Runs, republican paramilitary suspects who were given assurances that they were not being sought by police.

Prime Minister David Cameron has appointed a judge to lead a review that will report by the end of May.

Mr Robinson said: "I am glad that the prime minister made the statement that he did today.

Satisfied

"I very much welcome the judge-led inquiry that he announced and I am happy with the terms of reference that have since been set out."

The DUP leader added: "I am satisfied with the response that I have got from government.

Media playback is unsupported on your device Media caption Secretary of State Theresa Villiers said the letters "do not confer immunity and never did"

"I think the prime minister and the secretary of state have been prompt, they have dealt with the issues seriously and in a manner that is satisfactory to me.

"So yes, I do not intend to resign on the basis that if you get what you want why on earth would you want to resign?"

Mr Robinson had made his resignation threat after the trial of Donegal man John Downey collapsed.

Mr Downey denied killing four soldiers in the 1982 IRA Hyde Park bombing.

Mr Robinson denied that the crisis had been manufactured, and said: "If Sinn Féin were on the phones in our office they would know there was nothing synthetic about our concern over this issue."

There was never any amnesty or guarantee of immunity for anyone, and there isn't now David Cameron, Prime minister

Mr Cameron tweeted after his announcement of the inquiry earlier on Thursday: "I have just spoken to Peter Robinson. I told him I shared his anger over the Downey letter - and was glad we have agreed on an inquiry."

On Wednesday, Mr Robinson called for the letters to be rescinded. He also called for a judicial inquiry.

He said he was not prepared to remain as first minister in a power-sharing government "kept in the dark" about the letters.

Media playback is unsupported on your device Media caption David Cameron has announced an independent judge-led review

On the Runs included anyone suspected of, but not charged with, paramilitary offences committed before the Good Friday Agreement. They also included those who had been charged or convicted with offences but who had escaped.

Inquiry terms of reference Downing Street said the terms of reference of the judicial inquiry are to produce a full public account of the operation and extent of the scheme for On the Runs to determine whether any letters contained errors. The judge will be able to seek to interview anyone, but will not be able to compel witnesses to attend. Evidence will not be given in public. It will report by the end of May and will be able to make recommendations. The decision not to appeal the Downey case will not be altered by this inquiry.

'Full access'

Mr Cameron told a Downing Street press conference: "I agree with the first minister of Northern Ireland that after the terrible error of the Downey case it is right to get to the bottom of what happened.

"The case has already been referred to the Police Ombudsman, and, as the first minister has said, we should have a full independent examination of the whole operation of this scheme.

"We will appoint an independent judge to produce a full public account of the operation of this administrative scheme to determine whether any other letters were sent in error.

"The judge will have full access to government files and to government officials."

Mr Cameron said: "It is important to set out the facts of what has happened".

"When we came to power in 2010, we inherited a process where letters were sent, setting out the factual position on whether or not some individuals were wanted for questioning by the police.

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.

"This process continued under this government. There was never any amnesty or guarantee of immunity for anyone, and there isn't now."

Misunderstanding

He added: "It is right that we take swift action, but let us also remember that Northern Ireland has made great strides forward as a result of the peace process.

"It is vital that we deal properly with the events of the past but make sure this never undermines our determination to build a shared and prosperous future for the next generation so that we never again return to the horrors of the past."

However, the chair of Westminster's Northern Ireland committee, Laurence Robertson, said that the committee is "minded" to carry out its own inquiry.

He said he thought the inquiry Mr Cameron announced seems to be "too narrow" and was "wanting".

The committee's full decision would depend on "what else" the government can do, Mr Robertson added.

Earlier on Thursday, Tony Blair's former chief of staff said the crisis in Northern Ireland is based on a misunderstanding.

Jonathan Powell said the argument over the letters is "misplaced".

Northern Ireland's Deputy First Minister Martin McGuinness said all parties were aware of a scheme informing people they were no longer wanted by the police.

He said "information about this was in the political arena, and to a certain extent in the public domain".

Mr McGuinness also said that a meeting of the Policing Board in 2010 made clear that a scheme for On the Runs was in place.

"Everybody at that meeting knew that there was a scheme and that over a period of years that scheme was being proceeded with," he said.