The Taoiseach has said he wants to hear "all the sides" in the aftermath of revelations that senior republican Denis Donaldson has worked as a British spy for two decades.
The former head of administration in Stormont for Sinn Féin, Mr Donaldson (55) is one of the three men who had Stormont spy ring charges against them dropped last week.
The former senior Sinn Féin official confirmed he was a British spy just hours after party president Gerry Adams broke the news at a hastily convened press conference in Dublin yesterday afternoon.
Mr Donaldson's admission caused shock among republicans and prompted Taoiseach Bertie Ahern to urge the British government to explain what he termed the "bizarre" Stormontgate affair.
A Government spokeswoman said last night that Mr Ahern did not rule out seeking an inquiry into the issue, "independent of everyone", but first wanted to hear the British account of the affair.
The Taoiseach's office said today that Mr Ahen did not get an opportunity to meet British Prime Minister Tony Blair in Brusses, where EU leaders were gathered for a summit.
"However [the Minister for Foreign Affairs] Dermot Ahern and [Northern Secretary] Peter Hain have a scheduled meeting this Monday to discuss political developments where the issue of Denis Donaldson may arise", a spokesman said.
Speaking in Brussels this morning, the Taoiseach said: "This was a huge case, it doesn't get much bigger than bringing down democratically elected institutions that people have voted for. What this was about I just don't know.
"I'd just like to hear all the sides in this.
"Now we're asked to believe that the person Sinn Fein had in there looking after the administration was also in there by the British security.
"So he had the confidence of Sinn Fein and he had the confidence of British security to be in a key position that ultimately brought down the whole institutions. I tell you, it even stretches my imagination at 4am in the morning."
Last week, the North's Public Prosecution Service controversially dropped the spy-ring charges against Mr Donaldson and two other men on the grounds that it would not be in the public interest to proceed with the case.
The so-called Stormontgate affair involved police raids in October 2002 on Sinn Féin offices in Stormont and on a number of other premises in Belfast following a PSNI investigation into an alleged republican spy ring at
Stormont. Large quantities of documents were seized. David Trimble described the affair as "10 times worse than Watergate". The North's executive was suspended 10 days later.
The Ulster Unionist Party (UUP) said a public inquiry was now essential to explain the events.
"I think the only way to get the truth is a full public inquiry. There are so many unanswered questions," said a party spokesman.
The Democratic Unionist Party (DUP) also demanded more information.
"The reasons why this has come to light are not entirely clear and that's why I'm not buying the reasons that are being given at present. It is critical that we get a statement from the British government about this," said spokesman Ian Paisley Junior.
"I need to know, why if there was such a highly placed agent moving in the upper echelons of the Sinn Fein-IRA movement, were the IRA able to get away with so much murder over the last number of years and so much mayhem? That remains totally unexplained and unexplainable by this event."
Statement:Denis Donaldson
"My name is Denis Donaldson. I worked as a Sinn Féin Assembly group administrator in Parliament Buildings at the time of the PSNI raid on the Sinn Féin offices in October 2002 - the so-called Stormontgate affair.
"I was a British agent at the time. I was recruited in the 1980s after compromising myself during a vulnerable time in my life.
"Since then I have worked for British intelligence and the RUC/PSNI Special Branch. Over that period I was paid money. My last two contacts with Special Branch were as follows: two days before my arrest in October 2002 and last night, when a member of Special Branch contacted me to arrange a meeting.
"I was not involved in any republican spy ring in Stormont. The so-called Stormontgate affair was a scam and a fiction. It never existed. It was created by Special Branch.
"I deeply regret my activities with British intelligence and RUC/PSNI Special Branch. I apologise to anyone who has suffered as a result of my activities, as well as to my former comrades, and especially to my family who have become victims in all of this."