The RUC received detailed information about a planned attack in Omagh 11 days before a "Real IRA" bomb exploded in the town's centre, according to a draft report by the North's Police Ombudsman, Ms Nuala O'Loan.
The report is scathing of the police investigation into the attack which took place on August 15th, 1998. The explosion killed 29 people including a woman pregnant with twins. The Ombudsman is critical of the way the tip-off was treated and of the fact that intelligence was not passed to uniformed RUC officers in the town.
It alleges the atrocity might have been averted had police checkpoints been in place on the day of the explosion.
The Police Service of Northern Ireland (PSNI) said last night it had requested that the Ombudsman's office give it "a reasonable period of time to respond in detail with what we see as the serious deficiencies in this report". The PSNI emphatically denied that information provided by a double agent, using the name Kevin Fulton, or a tip-off on August 4th could have prevented the deaths.
The leaking of details comes at a sensitive time when policing is still top of the political agenda.
Ms O'Loan's draft report is understood to criticise the RUC's handling of the intelligence, saying "important investigative and evidential opportunities" were lost and the sharing of intelligence was "totally unsatisfactory". It says the information was deemed by RUC special branch not to refer to Omagh. This was a "significant error" which was "inexplicable and inexcusable".