Three men have been arrested over an incident in which a group of masked men were pictured in east Belfast this month.
At the time the incident was linked to an internal row within the loyalist paramilitary group the Ulster Volunteer Force (UVF).
Three men, aged 58, 56 and 34, have been arrested on suspicion of terrorism and other related offences.
Searches are being carried out in east Belfast and Lisburn, police have said.
The group, comprising dozens of individuals, was filmed walking in Pitt Park off the Newtownards Road on 2 February.
Police, who could be seen monitoring the scene and dispersing the crowd, said they responded to reports of “suspicious masked men”.
Det Ch Supt John McVea said: “Our investigation into the gathering at Pitt Park and activities linked to east Belfast UVF is continuing at pace and today’s arrests were conducted under the Terrorism Act.”
He said detectives would “continue to gather and examine all available evidence” in order to determine who was involved in the incident.
“I would appeal to anyone in the community who has information or footage regarding the incident or criminality in the area, to contact the police,” he added.