Relatives of those killed in the Omagh bombing have dismissed as "PR", the defence of the investigation made by Ulster police chief Sir Ronnie Flanagan.

The families of the 29 victims gave a news conference on Thursday after emerging from a two hour meeting with Flanagan saying they were unconvinced by his remarks and described his statement as a "cosmetic exercise".

"We have got to get to the truth," they said. "The people that planted the bomb continue to plan acts of murder are still out there. The fight for justice goes on. We feel that something drastic has to happen."

Lawrence Rush, who lost his wife in the Real IRA's attack, said he was not satisfied with the handling of the inquiry. Saying he was speaking only for himself, he commented: "I thought there was a bit of despondency in the room, and to me, Sir Ronnie Flanagan, good PR man that he is, has lost this battle."

He said Flanagan had defended a force "in which there are inadequacies, ineptitude and deceit". "It is time the police force, with all their resources and all their experience after 30 years of murder, finally came to their senses and put together a police force which is effective," said Rush.

William Gibson, father of another victim, said in a reference to Flanagan's leadership: "I would like him to do his job, that's what he should be doing and that's what he's there to do."

But Donna-Marie McGillion, who suffered serious injuries in the bombing, said she still had confidence in the investigation. "I always had confidence in the investigation, I don't believe anyone wants those people to go free," she said.

"I have always had confidence in the investigation and firmly believe they will do their best to secure convictions against these people."

Speaking ahead of a meeting with relatives of the 29 people who died in the worst bombing of the troubles, Flanagan had strongly rejected criticisms of the inquiry that had been made by police ombudsman Nuala O'Loan.

Published last December, O'Loan's report delivered a damning indictment of police actions before the bombing - as well as during the conduct of the subsequent investigation.

The report disclosed that police had been tipped off about an attack in Omagh 11 days before the explosion, but the information had not been passed on to local commanders who could have put checkpoints in place.

The report also described Flanagan's leadership during the investigation as "seriously flawed", which prompted the police chief to declare he would commit public suicide if he thought the allegations were correct.

Flanagan said Thursday's meeting with the victims' relatives would allow him to answer any questions they wish to ask.

"Sadly over recent weeks there has been so much distorted material in the public domain that I am here to see the people who really matter," he said.

"It is important that they have the opportunity today to ask us whatever questions they want to ask and to have answers to those questions."

Flanagan had been expected to present two documents responding to the ombudsman's critical report.

The first rebutted the "significant factual inaccuracies, misunderstandings, material omissions and unwarranted assumptions" made in the report.

The second addressed recommendations on the conduct of the on-going investigation.

The ombudsman recommended that the inquiry should be led by an outside officer, but Flanagan is set to appoint an outsider in an advisory capacity only.

Only one person has so far been convicted of the August 1998 bombing.

On Tuesday Colm Murphy was convicted of conspiring to cause the bombing in a Dublin court, and now awaits sentence.