SINN FÉIN has said it will meet the BBC to ask why it hasn't given news coverage to the Loughinisland film No Stone Unturned.
The documentary went on general release on Friday, selling out movie theatres across Ireland.
Three men alleged to have planned and carried out the attack on the Heights Bar in Loughinisland in 1994 are named for the first time in the film.
While it was reviewed by BBC Radio 4's The Film Programme, with an interview with director Alex Gibney, there has been criticism of BBC Northern Ireland's lack of news coverage.
The broadcaster has said "the tragedy of Loughinisland is a story BBC NI remains committed to covering and we will continue to make our own editorial judgements as to when we report any developments".
However, Sinn Féin's Chris Hazzard said it is “beyond belief that there should be such a glaring omission".
"As the MP for South Down I will meet with the BBC and challenge this editorial approach," he said.
Sinn Féin MLA Emma Rogan, whose father Adrian was one of the six men who died in the UVF attack, also wrote online: "Since the first screening of NSU (No Stone Unturned) in Belfast, the BBC has broadcast over 4,200 minutes or 70 hours of news and current affairs on TV and radio.
"Hundreds of stories have appeared online. In that time, not a single second or story was devoted to the Loughinisland film."
English journalist and campaigner Jemima Goldsmith, formerly Khan, has also tweeted about the issue to her 2.3 million followers.
"Latest @alexgibneyfilm doc exposes collusion in Northern Ireland... You won't see it on the BBC so go and watch in cinemas."
Former SDLP South Down MP Margaret Ritchie, who has also worked with the victims' families throughout their campaign, said the BBC must tell relatives why the film wasn't covered by local news and current affairs programmes.
"I will be writing to the BBC NI director Peter Johnston to ask why the film and its quite remarkable findings have not been covered to date," she said.
"Some 23 years later, it is now time that there is full transparency on the issue and that both the Irish and British governments pursue the issue of justice for the families to ensure that prosecutions and convictions take place.
"In this regard, I have written to both prime ministers urging the establishment of the Inter-Governmental Conference which would drive forward this important legacy issue and put pressure on the PSNI to bring forward prosecutions and convictions."
