Lawyers acting for the families of the three off-duty Scottish soldiers who were killed by the Provisional IRA in 1971 have threatened legal action to bring their killers to justice.

Fusilier Dougald McCaughey (23), Fusilier John McCaig (17) and Fusilier Joseph McCaig (18) were shot and killed in Belfast on 10 March 1971, prompting a political crisis in Northern Ireland.

It was the first killing of off-duty soldiers during The Troubles and led to calls for increased security measures in Northern Ireland.

The Three Scottish Soldiers Campaign for Justice claims the men responsible are living in Ireland and known to the authorities.

The new group said it will take “any necessary and appropriate legal action, including private criminal or civil prosecutions” against them.

Kris McGurk, director of the Three Scottish Soldiers Campaign for Justice, said: “John, Joseph and Dougald did not deserve what happened to them - they were just three young innocent boys. They do deserve our support and efforts to fight for justice on their behalf.

“The Troubles in Northern Ireland will never really end whilst we still have innocent victims troubled by them. This is why, if we want to move on we must provide closure for those victims and have those responsible for terror in our country held accountable for their actions.”

Matthew Jury, managing partner at McCue & Partners, added: “It is a terrible injustice that, time and time again, UK veterans are singled out for prosecution while IRA terrorists walk free.

“In this case, the authorities know the names of the soldiers’ killers, but still nothing is done. All the while, their families and loved ones are kept in the dark. They have the right to know the truth and to see those responsible brought to justice.”