DUP leader Sir Jeffrey Donaldson has questioned why Northern Ireland was not "given its proper title" after conference literature used at the Labour Party conference in Brighton referred to the "North of Ireland".
A fringe event hosted by Sinn Féin yesterday evening referred to Labour’s Louise Haigh as "Shadow Secretary of State to the North of Ireland".
The event, entitled A Decade of Opportunity – Towards a Shared Ireland, featured speakers including Ms Haigh, South Down MP Chris Hazzard and Newry and Armagh MP Mickey Brady.
"North of Ireland" was also used in parts of Labour’s official conference guide.
Sir Jeffrey told the Daily Telegraph that the description "demonstrates a lack of maturity on the part of Sinn Féin", which appeared to have been "overlooked" by Labour.
"Hopefully next time they will ensure that Northern Ireland is given its proper title," he said.
It is understood that the listing was submitted by Sinn Féin and was not signed off by Ms Haigh.
Ahead of the event, Mr Hazzard joked that all publicity was welcome.
"Expect the event will be bunged out the doors now," he tweeted.
SDLP leader Colum Eastwood tweeted: "I really don't get this latest unionist outrage about the name of this place.
"Call it whatever you want. If you're annoyed by someone using a different name than you then you probably need to get a life. It would be a lot better if we all agreed to share the place."
In July, Sir Keir said he would campaign for Northern Ireland to remain part of the UK if there was a border poll in his lifetime.
“I personally, as leader of the Labour Party, believe in the United Kingdom strongly, and would want to make the case for a United Kingdom strongly and will be doing that,” he said.
