A senior PSNI officer has told the Omagh Bombing Inquiry that the RUC did not have enough trained staff to properly use the police computer database during the investigation into the 1998 atrocity.

Detective Chief Inspector Neil McGuinness said on Tuesday that the number of officers trained in the Home Office Large Major Enquiry System (Holmes) was insufficient for the scale of the Omagh inquiry. He said there had been only one Holmes liaison officer to oversee training and resources, and that post remained vacant for a period after November 1997.

McGuinness accepted there were “significant failings in respect of the operation of Holmes One during the Omagh Bombing investigation.” He said the RUC did not comply with all aspects of the Major Incident Room Standardised Administrative Procedures (MIRSAP) and that this could have led to missed opportunities in diverting resources, saving time, or following lines of inquiry.

The Real IRA car bomb exploded in Omagh, County Tyrone, on August 15, 1998, killing 29 people, including a woman pregnant with twins. It was the worst single atrocity of the Troubles in Northern Ireland, coming less than three months after the Good Friday Agreement was approved in a referendum.

The public inquiry, chaired by Lord Turnbull, is examining whether the bombing could have been prevented by UK state authorities. Its current phase of hearings is looking at the period before and after the attack and how the investigation was conducted.

McGuinness said the Omagh investigation was unprecedented in scale and that experienced RUC detectives had mainly dealt with the Provisional IRA during the Troubles, not dissident republican groups like the Real IRA. He said the force faced new challenges with this investigation.

Earlier, journalist Greg Harkin gave evidence about an article he wrote in July 2001 that triggered a Police Ombudsman review of the original RUC investigation. Harkin said the article, based on information from confidential sources, stated that the RUC had received a warning three days before the bombing that a large bomb was being transported from the Republic of Ireland.

Harkin said he did not contact police for comment before publication and that then RUC Chief Constable Sir Ronnie Flanagan called him the night before the article appeared. Harkin said he stands by the article and has no regrets about publishing it.

The inquiry continues in Belfast.