The Government and the Garda have said there is "no foundation" to allegations that the Garda knew about the 1998 Omagh bomb in advance and that the Government did a deal with the "Real IRA" afterwards.
Britain's Channel Four News last night reported two key allegations which, if true, would be seriously damaging to the Garda Síochána and the Government. Both allegations, it says, have been made by a "guilt-stricken" Garda detective sergeant.
However, when these allegations first emerged some months ago the then minister for justice, Mr O'Donoghue, said this Garda detective sergeant was under suspension and faced criminal charges over unrelated matters. He said the behaviour of this officer would be examined by the tribunal examining allegations of corruption about policing in Donegal.
Mr O'Donoghue received the allegations in a report from the Police Ombudsman for Northern Ireland, Ms Nuala O'Loan. Mr O'Donoghue set up a three-person group to examine the allegations, and a report from it is expected within a month.
The first of the allegations - which have been made with varying degrees of detail in British newspapers over the past few months - is that the Garda authorities knew a major car bomb was going to be brought to Northern Ireland in a stolen car days before the Omagh bomb exploded.
According to this claim, a very senior Garda ordered that the stolen car and its cargo be allowed into the North unhindered to protect the source of the information.
The source had provided information that led to the successful interception of a number of large car bombs before and the decision to allow the Omagh one through was made to prevent the source - who was responsible for stealing the cars used - from coming under suspicion by the "Real IRA".
The second allegation, also made by the detective sergeant, is that a Government minister did a deal with the "Real IRA" immediately after Omagh that in exchange for a ceasefire, its members would not be harassed or "subject to undue attention" by the Garda. The programme claimed to have court documents showing that charges against alleged "Real IRA" members were subsequently dropped by the Garda without explanation.
A Garda spokeswoman said last night the allegation that there was prior knowledge of the car being used for the Omagh bombing was "without foundation". The spokeswoman said the allegation appeared "to emanate from a mischievous source" but did not elaborate on this.
"The Garda Síochána and the Police Service of Northern Ireland had and continue to have an excellent working protocol in all areas of law enforcement, particularly so insofar as intelligence on criminal or terrorist activity is concerned," the spokeswoman said. "Any suggestion to the contrary is ludicrous."
She said the Garda Commissioner was concerned "that any such allegations would be a source of anxiety to any relatives of those tragically killed or injured in Omagh".
A Government spokesman said allegations concerning a deal between the Government and the "Real IRA" to "go easy" on the organisation in exchange for a ceasefire were also "without foundation". Government sources pointed to the conviction since of one person in connection with Omagh, as well as the imprisonment of 30 other "Real IRA" members on various charges.