A row has broken out between Northern Ireland’s Chief Constable and a former police watchdog after she said the Omagh bomb could have been prevented.

Former ombudsman Nuala O’Loan investigated police actions in the lead-up to the bomb and, in a report published in 2001, said she did not know whether the bomb could have been prevented.

However, speaking on Wednesday morning, the 20th anniversary of the blast which killed 29 people, including a woman pregnant with unborn twins, Baroness O’Loan said she now believes it could have been stopped.

But Police Service of Northern Ireland chief George Hamilton has insisted officers could not have prevented the blast.

“The former police ombudsman, Baroness Nuala O’Loan, has today alleged it is her firm view that the bombing could have been prevented,” he said.

“I consider this comment to be inaccurate, unfair and unreasonable.

“Police were not in a position to prevent the Omagh bombing.”

He added: “I do not know what has led Baroness O’Loan to a conclusion that differs so much from her remarks of 2001.

“Considerations around a public inquiry into the Omagh bombing are a matter for Government.”

Baroness O’Loan later responded to Mr Hamilton remarks, standing by her comments.

“It is my understanding of the further information which has emerged, some of which I am not in a position to talk about, but we have seen work by very prominent journalists and we have seen the various inquiries by (Sir  Peter) Gibson and people like that,” she said.

“And we can see Gibson very carefully choosing his language about the reasonableness of the police actions in disclosing or not disclosing intelligence.

“We know that 78% of the intelligence was not disclosed, we know that there is a body of evidence and intelligence now about the tracking of people, intercepted telephone calls, so there is a lot more.

“It doesn’t come easy to me to say this, I feel profoundly saddened, but I think that if you have a view which is informed by experience of investigation, of systems, then you do have certain duties and I think it was incumbent on me to say this.

“And I think the time is right now when we can look at it.”

Twelfth of July celebrations – LondonderryPSNI Chief Constable George Hamilton said he did not wish to say more out of respect for grieving families on the 20th anniversary of the Omagh bomb (Brian Lawless/PA)

“Now it just seems to me that we need to learn the lessons of the failings north and south that allowed this bomb to travel up in the way that it did and which allowed it to be planted in the middle of a little market town on a glorious summer afternoon,” she told BBC Radio Ulster’s Talkback programme.

“And I think the only way we will do that is through a public inquiry with full powers to compel witnesses and compel evidence, but it won’t work if it’s a UK public inquiry, the story vests in both territories, Northern Ireland and the Republic, and indeed in England.”

Omagh bombing 20th anniversarySpanish tourist Gonzalo Cavedo, who survived the Omagh blast, stands in front of the car containing the bomb, in an image found by police on a camera among 30 tons of rubble removed from the scene (RUC/PA)

Mr Hamilton said he did not wish to say any more on the matter out of respect for those remembering their loved ones.

“This is a day for remembrance and reflection and, out of the deep respect I have for the grieving families, I do not intend saying anything additional to my comments regarding the Omagh bomb this morning and to which I am addressing in this statement,” he said.