Arlene Foster has hit out at Sinn Féin for making an IRA commemoration "sound like a fun day out for all the family".
The former DUP leader also accused Sinn Féin MP John Finucane, who is billed as the event's main speaker, of "glorifying terrorists".
Mrs Foster shared an image online of a poster advertising the "South Armagh Volunteers Commemoration" on June 11, assembling at Mullaghbawn Community Centre.
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The Sinn Féin-branded poster includes an image of North Belfast MP Mr Finucane and it says there will be "music, refreshments and kids' entertainment".
Above the poster is another banner entitled "Roll of Honour - South Armagh Brigade" in which 24 names are listed including IRA hunger striker Raymond McCreesh.
It also includes a quotation from former Sinn Féin vice-president and Cumann na mBan commander Máire Drumm, who was shot dead by loyalists in 1976.
Former First Minister Mrs Foster tweeted: "For all those fawning over Sinn Féin, here is one of their MPs glorifying terrorists and making it sound like a fun day out for all the family."
Sinn Féin was approached for comment.
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