It is the first time the ex-RUC Chief Constable has publicly said sorry for the botched investigation into the atrocity that claimed the lives of 29 people.

Sir Ronnie said he would not resign from his current role as top Home Office advisor on policing, despite a judge's recent condemnation of how the RUC investigated the August 1998 bombing.

Last month South Armagh man Sean Hoey was cleared of the Omagh murders and a series of other dissident republican attacks.

In setting the 39-year-old electrician free, trial judge Mr Justice Weir delivered a damning assessment of the RUC. He highlighted malpractice at every stage of evidence gathering procedures during the case.

Sir Ronnie said he would not step down as head of Her Majesty's Inspectorate of Constabulary. But he did admit responsibility for the RUC's failures under his command.

"I absolutely publicly apologise to the families in Omagh," he told Channel Four news. "I am desperately sorry that we have not at this point brought people to justice for that dreadful attack. I publicly apologise to all those families and all those victims; to all those who were injured, without reservation.

"Of course as Chief Constable, I have to take responsibility for the shortcomings that the judge highlighted and I take responsibility for those shortcomings".

Asked if he would resign, Sir Ronnie replied: "I don't think that is appropriate."

The senior police officer was speaking after a meeting Victor Barker, who lost his 12-year-old son James in the bombing. Mr Barker, who has been demanding Sir Ronnie's resignation, said the apology didn't go far enough, saying: "He apologised that no-one's been brought to justice, that's very different from apologising for his own involvement in the case."