Loyalists have been accused of trying "to mark out territory" after images of masked men marching through a public park in Co Tyrone were posted online.
Pictures have emerged of a gang patrolling Dungannon Park on the outskirts of the town last week.
It is believed up to 15 men may have been involved in the sinister show, which is being linked to a clash in the park between two factions last Tuesday.
The emergence of the images later prompted the PSNI to say it will not tolerate "vigilante activity".
A spokeswoman last night said that no arrests have been made "at this time" and that "enquiries continue".
One image circulated on social media included a picture of the masked gang and the words "Moygashel loyalists will never let our community live under the threat of foreign criminals".
Posters glorifying the UVF have previously been put up in the village, which is on the outskirts of Dungannon.
Fermanagh South Tyrone Sinn Féin MP Michell Gildernew last night condemned the display saying it "is nothing short of intimidation and an attempt to mark territory".
"There can no absolutely no place for racism, xenophobia or any form of discrimination in our society," she said.
The MP appealed for calm and called on those "in positions of influence in political unionism to demonstrate measured and responsible leadership before someone is killed or seriously injured by loyalist criminal gangs"
She also urged the PSNI to do all its power to ensure "there is no repeat of this intimidation."
Aontú councillor Denise Mullen, who voiced concerns earlier this week, said: "I see it as them marking out their own territory.
"The park is a place for all communities, a council owned and maintained facility."
"Loyalists refer to the 'naitonalist end of the town'," she said.
"Is there a nationalist end of the town? Dungannon is multi-denominational and multi-cultural."
