Members of the Parachute Regiment have always been held responsible for the victims' deaths
The Ulster Volunteer Force is set to claim it shot some of the 10 people killed in a west Belfast neighbourhood nearly 50 years ago.
Members of the Parachute Regiment have always been held responsible for the civilians' deaths during three days of gunfire involving soldiers at Ballymurphy in August 1971.
But "veterans" within the loyalist paramilitary organisation have identified a UVF sniper they say carried out a number of the shootings, according to an informed source.
With an inquest scheduled to start in September, the information is to be provided to the Coroners Service within days.
One of those aware of the process described it as an attempt to shed some light on one of the most chaotic and notorious killing sprees during the Troubles.
The shootings occurred amid disturbances sparked by the introduction of internment without trial in Northern Ireland.
Ten people were shot dead, including a priest trying to aid one of the wounded and a mother-of-eight. Another man later died of heart failure.
Bereaved families have come to refer to the killings as the Ballymurphy Massacre'.
In a potentially major development, loyalists who were active at the time have come forward with the new allegations.
They approached an interlocutor to claim a UVF sniper located in the neighbouring Springmartin estate opened fire into Ballymurphy.
It is understood these paramilitary veterans have provided the gunman's name, alleging he was responsible for a number of the deaths.
Information has also been supplied on the rife allegedly used, along with its subsequent seizure by the authorities.
"These men are adamant that if ballistic tests are carried out on the weapon it will establish that the UVF sniper did cause casualties, possibly fatal," the source said.
The interlocutor has now contacted a Belfast solicitor to discuss how the information is supplied to the Coroners Service.
Billy Hutchinson, leader of the Progressive Unionist Party, which has links to the UVF, claimed it was a significant move which could help provide clarity around what happened at Ballymurphy.
The Belfast councillor added: "The IRA should reciprocate and declare what, if anything, it knows about the events over those days."
Padraig O Muirigh, a lawyer who represents a number of families bereaved in the Ballymurphy shootings, said: "Any new evidence relating to this inquest should be brought to the attention of the Coroner as a matter of urgency, and in due course we will review this evidence in preparation for the inquest."