In 1971 three Royal Highland Fusiliers, Dougald McCaughey, 23, and teenage brothers John and Joseph McCaig, were off-duty and in civilian clothes when they were enticed from a Belfast pub and shot.
The controversy started after a Twitter user asked John Mason to support a campaign to bring the soldiers' killers to justice.
John Mason replied with the following:
@Albion_Rover Happy to support all campaigns to bring about justice. But not taking sides between Irish and British.— John Mason (@JohnMasonMSP) January 29, 2017
John Mason was quizzed as to why he couldn't take sides between Scottish soldiers and Irish murderers.
John Mason replied with:
@Albion_Rover You say Irish murderers. Others say Irish freedom fighters. I support Scottish soldiers if they do good but not if they do bad— John Mason (@JohnMasonMSP) January 30, 2017
Democratic Unionist, Nelson McCausland, said:
“Will Mr Mason clarify what he believes these soldiers were ‘doing bad’ when they were lured from a bar to be murdered? Are the SNP happy to align with a terrorist campaign because those who engaged in it share their aim to break up the UK?”