According to reports, several men with masked faces were seated in the gallery during the trial of James Smyth, 57, who is accused of murdering Eamon Fox, 41, and Gary Convie, 24, in May 1994.

The trial has notably heard evidence from UVF “supergrass” Gary Haggarty.

The masked men were present during the morning of Monday’s court hearing but left at the start of the afternoon after the presiding judge warned that anyone covering their face would be removed, the Belfast Telegraph reports.

In a statement, the Lady Chief Justice’s office said: “The Lady Chief Justice considers that this was not acceptable and should not have happened. The judge dealt with the matter appropriately when it was brought to his attention.

“The Lady Chief Justice has asked NICTS to identify how this incident occurred.”

Pádraig Ó Muirigh, solicitor for the Fox and Convie families, said: “The presence of individuals with face coverings and baseball caps in the public gallery created an intimidating atmosphere for the families of the deceased.

“This is unacceptable in a court of law and I made police aware of these concerns.”