Northern Ireland First Minister Arlene Foster is to write to the Dáil's Ceann Comhairle regarding a tweet sent by a Sinn Féin TD.
TD for Laois/Offaly Brian Stanley sent a tweet yesterday celebrating two historical IRA attacks on the British army.
The tweet has since been deleted, but was described as "shameful" by DUP leader Ms Foster.
Mr Stanley, who is also the chairman of the Dáil's Public Accounts Committee, sent the tweet on the centenary of the Kilmichael ambush in 1920.
He wrote to his 3,700 followers: "Kilmicheal (sic) (1920) and Narrow Water (1979) the 2 IRA operations that taught the elective of (the) British army and the establishment the cost of occupying Ireland. Pity for everyone they were such slow learners."
The Kilmichael ambush was an attack carried out by the IRA during the War of Independence in which 17 members of the Royal Irish Constabulary Auxiliary Division were killed.
The Narrow Water ambush took place during the Troubles and saw 18 British soldiers killed by the IRA near Warrenpoint, in 1979.
The attack took place the same day the IRA killed Lord Louis Mountbatten by blowing up his fishing boat off the coast of Mullaghmore in Co Sligo.
Two members of his family and Co Fermanagh teenager Paul Maxwell, who was working on the boat, also died.
Lord Mountbatten was a second cousin to Britain's Queen Elizabeth and had served in two world wars.
Ms Foster said it was her intention to raise the tweet with the Ceann Comhairle.
She tweeted: "I will be writing to the Ceann Comhairle of the Dáil about this shameful tweet.
"Although deleted, it is outrageous that someone with such warped views can hold a senior position in the Dáil. SF talk about respect & equality but there's not much sign of respect for victims."
Mr Stanley's tweet received more than 500 likes on the platform and was shared close to 400 times.