Families bereaved in the 1971 McGurk's Bar bombing have stepped up pressure on the chief constable to accept the findings of police wrongdoing in the case.
An investigation by the Police Ombudsman found the RUC had an "investigative bias" by claiming the loyalist attack was a republican bombing, which was then not properly investigated.
Relatives of the 15 people killed in the blast staged a protest at the Policing Board headquarters demanding Chief Constable Matt Baggott, who had originally cited other investigations which he said had come to different conclusions on police conduct, make his position clear.
The families delivered a suitcase filled with files on the case, in a symbolic gesture on the misinformation around the bombing and demanding a response from the police chief.
Ciaran MacAirt, whose grandmother Kitty Irvine was killed in the explosion, said Mr Baggott had been shown files on police handling of the case which relatives had obtained. But Mr MacAirt said that since that meeting, no follow-up discussions had been granted.
"We want to know now what he has a problem with," he said. "But for three months he has denied us a follow-up meeting. We are now putting the onus on him. It is as if he has become a new chapter in our fight for the truth."
The bombing was carried out by the UVF, but had initially been presented by the RUC as an accidental "own goal" by the IRA, prompting speculation that the dead may have included IRA members who were carrying the device.
In a statement issued following the families' latest protest, the police said: "In March, following the publication of the Ombudsman's report into the McGurk's Bar bombing, the chief constable met with a number of families and their representatives to listen to their concerns.
"This meeting was held in private and at the request of the families we agreed not to discuss in public any details of this meeting. However, we did give an undertaking to consider the Ombudsman's report in detail and then meet with the families again. Over the past three months we have worked diligently, and the Historical Enquiries Team, who were tasked to reopen the investigation, continue with their work to ensure that all possible lines of investigation have been pursued."
It added: "Our priority remains to ensure that our investigation and analysis is carried out objectively and expeditiously. In view of the complexity of this undertaking, and the ongoing challenges for policing, this has taken some time to complete thoroughly. The chief constable's offer to meet with the families on completion of this work remains open."