The Republic's Foreign Minister has said he is very concerned and surprised about allegations that officials in the south were poaching foreign investment from Northern Ireland.
Stormont First Minister Arlene Foster levelled the claim at her DUP conference on Saturday and also said concerns in Dublin about Brexit were driven by political instability.
Charlie Flanagan said he rang Northern Ireland's DUP Economy Minister Simon Hamilton to raise the accusation.
"I'm very concerned at these remarks," he said.
Mr Flanagan also said he was "very concerned at the claim that representatives of the Irish Government where allegedly talking down the Northern Ireland economy".
He added: "I'm concerned that allegations of representatives of the Irish State were in any way poaching business."
In her speech to the DUP faithful, Mrs Foster said relations with Dublin were as good as they ever had been.
But she warned ties with the European Union were not as important as the benefits of being in the UK.
Mr Flanagan addressed the row after holding talks with US Secretary of State John Kerry as the key White House figure collected the Tipperary International Peace Prize for 2015.
Mr Kerry warned about risks to the Northern Ireland peace process if there were changes to the border with the Republic on the back of Brexit.
"People need to be really careful with downstream consequences, that one choice can have an impact on other aspects and whatever happens to the border, how that border access is managed," Mr Kerry said.
"It's really critical that it be done very thoughtfully and very sensitively so that it does not have any impact."
Mr Kerry declined to discuss the revived FBI investigation into emails linked to Hillary Clinton just days out from the US Presidential election.
He said he had not been notified of the new inquiry in advance and that he had not been asked for information.
The US Secretary of State also raised the war in Syria and said he hoped peace talks could begin in the next few months.
"I want to be very, very careful with any kind of prediction," he said.
"But broadly put, is it possible?
"Yes it's possible. Provided Russia and the Iranians and the regime itself are willing to accept a reasonable approach put on the table by all sides, by all the other parties, in the hopes of being able to move toward that political discourse."
Mr Kerry added: "We are not going to stop, not for one day, without any shame whatsoever in saying that."