An SAS soldier involved in the lethal ambush of two IRA men was also present when his military colleagues shot dead a Protestant taxi driver, a court heard on Tuesday.
Lawyers claimed the disclosure should have come earlier to allow questioning at the inquest into the double killing of republicans Martin McCaughey and Dessie Grew.
McCaughey’s sister, Sally Gribben, is continuing to challenge a conclusion that the shootings near Loughgall, Co Armagh in October 1990 were justified.
Her appeal against a previous failed legal bid to have the inquest verdicts quashed is to be heard later this month.
In court it emerged that a member of the SAS unit who opened fire on the IRA men and identified only as Soldier D was also involved in an earlier operation that resulted in civilian Kenneth Stronge being fatally wounded.
Mr Stronge, 46, died after being shot as he drove his taxi past an RUC base at North Queen Street in Belfast in July 1988.
Four members of an SAS team had opened fire on IRA men as they launched a rocket at the barracks from another nearby car.
With more than 80 high velocity bullets fired at the attackers, Mr Strong was hit and critically wounded. The innocent victim died three days later.
Counsel for Ms Gribben revealed the link between the two incidents based on new disclosure from the Ministry of Defence.
Karen Quinlivan QC told the Court of Appeal: “Soldier D was involved in the incident of the shooting of Kenneth Stronge.
“Although he did not deploy his weapon, he was one of six officers (present).”
The development came amid final preparations for the bid to overturn a previous judgment on the McCaughey and Grew inquest.
The two men were killed after being ambushed at farm buildings.
Although both armed neither of them fired any shots, provoking claims that soldiers could have made arrests.
With the appeal listed for April 26, the McCaughey family’s lawyer stressed the potential significance of the new disclosure.
Fearghal Shiels of Madden & Finucane Solicitors said outside court: “We contend that the involvement of Soldier D in the fatal shooting of Kenneth Stronge, in which soldiers in the unit of which he was a member fired in excess of 80 rounds in a densely populated urban area, is indicative of the propensity of undercover soldiers to deploy excessive and unjustified force.”