Northern Ireland's chief constable has rejected calls to bring in two independent officers to head a new inquiry into the Omagh bombing at a meeting with bereaved relatives.

Sir Ronnie Flanagan met with the relatives on Thursday to deliver his response to the Police Ombudsman's report which was highly critical of the way the police investigation into the atrocity had been handled.

A Real IRA bomb in August 1998 killed 29 people, including a woman pregnant with twins.

It was the single worst atrocity in 30 years of the Troubles.

Mistakes have been made, but none have reduced the chances of success Sir Ronnie Flanagan

The chief constable's report admitted some mistakes had been made in the investigation.

However, he maintained his officers had done everything in their power to catch the men who were responsible.

Sir Ronnie was also highly critical of the way the Police Ombudsman Nuala O'Loan's investigation was carried out.

He said the police service was prepared to work alongside the ombudsman's office, but that a better understanding of each other's roles was needed if they were to work effectively.

"The police service in its turn is entitled to expect from the ombudsman's office the same high standards of professionalism, rigour, openness and fairness that are, rightly, expected of the police," he said.

The report also accused Mrs O'Loan of failing to give officers the chance to defend themselves in the course of her investigation.

Nuala O'Loan was scathing of the police handling of Omagh

He said Mrs O'Loan's report contained serious errors of fact and omission, and had "done a grave disservice and caused great hurt" to his officers.

"It has inflicted unnecessary grief and anxiety on the relatives of those murdered in Omagh and those injured," he added.

"The errors, inaccuracies and misunderstandings it contains have also seriously distorted the facts about the events surrounding the Omagh bomb and its investigation."

The report also states that the ombudsman had much to learn from her own investigation as had the police service.

Nuala O'Loan launched an inquiry into the police handling of the investigation following reports that Special Branch had failed to act on a warning received three days before the bombing.

Sir Ronnie: "The report has caused great hurt to the police service"

The police informer known as Kevin Fulton, claimed he told special branch that dissident republicans were planning some sort of attack in Northern Ireland.

A second warning was uncovered during the course of Mrs O'Loan's investigation which showed that on 4 August police were told that terrorists were about to target Omagh.

The ombudsman's report found that the information was never passed on to senior police officers in Omagh.

However, Mr Flanagan has defended special branch's role in the investigation.

He said Mr Fulton was an "unreliable and highly erratic" informer.

He added that his officers, even if they had acted differently, could not prevented the bombing.

Intensive search

"To suggest otherwise not only does a grave injustice to police officers who acted professionally throughout, but has also caused deep and unwarranted distress to the families of those murdered, and to the injured."

Superintendent Brian McArthur, who has headed the inquiry for the past 18 months will remain in charge of the investigation with a senior officer from Merseyside being introduced to "quality assure" the investigation.

Sir Ronnie said the search for the Omagh bombers was still intensive and would continue to try to unearth new evidence.

"Mistakes have been made, but none had reduced the chances of success," he said.

"I recognise fully the sense of loss, frustration and need for justice for all those affected.

"They have my assurance that the commitment of the Police Service of Northern Ireland to bring those responsible for Omagh to justice."