The Taoiseach meets a Sinn Féin delegation in Dublin this morning and will face demands to confront the British government over collusion between security forces and loyalist paramilitaries.
The party's chief negotiator, Mr Martin McGuinness, said yesterday that their allegations had once been dismissed and ignored.
"For decades Sinn Féin pointed out that the British intelligence was manipulating, controlling and directing loyalist death squads as the deniable arm of the British war machine," he said.
"Recent revelations" - a reference to the 19-page interim report by Sir John Stevens who is investigating the murders of Pat Finucane and Adam Lambert - proved the Sinn Féin case, Mr McGuinness said.
"This is a damning indictment of the role of British intelligence and the Special Branch in their war against Irish republicans and nationalists," Mr McGuinness said.
"The Stevens investigation produced a report which ran to thousands of pages," he added. "Only 19 pages of this have been made public, yet this is an issue of the deepest public concern. The Irish Government, acting on behalf of - and in the interests of - Irish citizens should have full access to this report in its entirety."
Referring to specific cases, Mr McGuinness said Mr Ahern should demand of the British government full disclosure of the activities of undercover agents throughout the past 30 years.
He said the Dublin-Monaghan bombings and the killings of Séamus Ludlow in Co Louth and Eddie Fullerton in Co Donegal merited special attention.
"The British government at the highest political level sanctioned the activities of British intelligence. The Irish Government must challenge the British government on this. The Irish Government must challenge and demand an end to the continued activities of these agencies in Ireland."
Making clear he was not seeking judicial inquiries, he added: "The Irish Government, on behalf of Irish citizens North and South, must demand that the files of these agencies are now opened to full scrutiny."
His call came as anti-agreement Ulster Unionist sources warned they will call for another meeting of the party's ruling council if the two governments' Joint Declaration is not rejected.
The document, drawn up in marathon talks at Hillsborough in March, has been scrutinised by four UUP committees, who will present their findings at a meeting today.
Each committee has been examining an issue relating to demilitarisation or "normalisation", on- the-run fugitives or OTRs, sanctions to be used against parties held to be in breach of the Belfast agreement, and policing and the administration of justice.
Senior UUP figures, including the Lagan Valley MP, Mr Jeffrey Donaldson, are known to be hostile to the Joint Declaration and its provisions.
There are suggestions that some unionists are unhappy with plans to proceed with elements of the package not specifically linked to what Mr Tony Blair calls "acts of completion" by paramilitaries.
A reconvened Ulster Unionist Council will be viewed as fresh pressure on the party leader, Mr David Trimble.