Northern Ireland's First Minister Peter Robinson has requested the recall of the devolved Assembly after claiming a government deal that saw IRA terror suspects assured they would not be prosecuted also involved the granting of royal pardons.
Mr Robinson had already warned the Government he will resign unless a public inquiry is ordered into the controversy that has been triggered by the collapse of the Hyde Park bomb case.
Tonight the Democratic Unionist leader said the contents of a motion he would put before the Stormont Assembly during a specially convened session on Friday would depend on how the Government responded to his demand.
Mr Robinson issued the effective deadline ultimatum as he emerged from a meeting with Northern Ireland Secretary Theresa Villiers at Hillsborough Castle.
He earlier expressed outrage that he and other Stormont ministers had been left in the dark over the secret deal that saw government letters of assurance given to more than 180 Irish republican paramilitary suspects which led them to believe they would not be prosecuted.
Mr Robinson said he now understood pardons had also been granted.
"It appears that we are not just dealing with on-the-runs who received letters but we are also dealing with people who received the Royal Prerogative of Mercy, that indicates there were offences involved," he said.
"So we are not talking just about people who it is believed that the police did not have sufficient evidence to make a prosecution stick - that makes it a very serious matter."
The details of the deal emerged during the failed prosecution of John Downey, from Donegal, over the Hyde Park attack.
The 62-year-old denied murdering four soldiers in the 1982 bombing.
The case against him was ended because government officials mistakenly sent him a letter in 2007 telling him he was no longer a wanted man.
Prime Minister David Cameron condemned actions that led to the withdrawal of the prosecution case as a "dreadful mistake".
While the mistakes that resulted in Mr Downey receiving the letter have led to an apology from the Police Service of Northern Ireland (PSNI), a political crisis has erupted at Stormont over the wider issue of why the Government was sending out any assurance letters and allegedly without the knowledge of the majority of Stormont politicians.
The deal was apparently struck between Sinn Fein and the previous Labour government after an effort to legislate on the issue of on-the-runs (OTRs) failed.
But of 187 letters sent out, 38 were issued since the coalition Government took power in 2010.
With justice powers having being devolved back to Stormont just before the last general election, the anger of many Assembly members has been intensified by the fact the policy seemingly continued to be pursued by the Northern Ireland Office when law and order responsibilities rested with the power-sharing Executive.
Mr Robinson expressed hope that Prime Minister David Cameron would response positively to his call for an inquiry into the wider issue.
"I am asking for what is necessary and I don't think the Conservative Party is a party that will want to defend or support or hide those who have been responsible for terrorism, so I have high hopes that I am not asking for the impossible," he said outside Hillsborough Castle.
"I think if you consider the Prime Minister's demeanour in the House of Commons today he is clearly very angry about the issue and I hope that takes the form of being prepared to do something that it's clear that we can get all the information out and we know exactly what happened and who was responsible."
Stormont Justice Minister David Ford also met Ms Villiers in a separate meeting tonight.
He said he had received assurances that his devolved department had played no role in sending the letters.
"The Department of Justice has not been involved in sending out any amnesty letters and it will not be involved in doing so as long as I remain minister," he said.
Mr Ford, the leader of the cross-community Alliance Party, also backed Mr Robinson's request to recall the Assembly.