The police ombudsman's office has stood by its claim that the RUC failed to properly investigate the murders of 15 people in McGurk's bar bomb in 1971.
On Monday police chief constable, Matt Baggott, questioned the claim that the RUC was guilty of investigative bias.
The ombudsman's director of historic investigations, Paul Holmes, said they stood by their findings.
"We were very clear that there was a confusing intelligence picture," he said.
"But in terms of evidence it pointed towards the involvement of a loyalist group.
"We were clear as well that police investigating the bombing concentrated on the theory that republicans had been responsible as opposed to loyalists and this distracted them from a thorough investigation at the time.
On Tuesday a SDLP MLA claimed the chief constable had damaged the police's reputation by not apologising for the RUC's investigation into the McGurk's bomb.
Mr Baggott has expressed sympathy, but did not apologise over the 1971 attack.
Alban Maginness told an Assembly debate he had "immense respect" for Matt Baggott, but that he had been "badly advised" over his comments.
"He should have taken the example of David Cameron when the Bloody Sunday report came out and apologised immediately and without qualification," Mr Maginness said.
He added that "whoever penned that statement" did not reflect Mr Baggott's "fine qualities" and that he should meet the McGurk's families as soon as possible.
"Unfortunately this is damaging not only to his standing but also to the standing and the reputation of the PSNI," Mr Maginness added.
The bomb exploded at the bar at Great George's Street in north Belfast killing 15, including three women and two children, and injuring more than 16 others.
In the aftermath, RUC officers briefed politicians and the media that the atrocity was an IRA "own goal" when in fact loyalists were responsible.
In 1978, UVF member Robert Campbell was convicted of his part in the attack.
The chief constable was also criticised by Sinn Fein MLA Gerry Kelly who said he should say sorry to the relatives of those who died.
"Matt Baggott had I think, an opportunity, to apologise," he said.
"The families showed absolute dignity in their presentation yesterday and to be slapped in the face by the present chief constable is an abominable and disgraceful way to behave"
DUP MLA for North Belfast, Nelson McCausland said that he welcomed the publication of the report nd particularly noted that it had ruled out collusion between the loyalists responsible and the RUC.
He said that he hoped the McGurk's survivors and families of those who died would find closure through the report.
He said earlier comments by Mr Kelly had a "certain irony".
"The IRA has a lot of information about murders that it carried out," he added.
"And there are lots of families that are waiting for closure and I would make an appeal for people to be honest about the past and help in that process of closure."