Democratic Unionist Party (DUP) person Sir Jeffrey Donaldson has accused the Irish authorities of "harming" Northern Ireland's narration with the remainder of the UK done its enactment for the Brexit deal.
His remark came aft helium met Taoiseach (Irish Prime Minister) Micheál Martin.
Their gathering successful Dublin was their archetypal since Sir Jeffrey became DUP leader.
Mr Martin said helium accepted unionists had "genuine concerns" implicit post-Brexit arrangements for Northern Ireland.
But Sir Jeffrey warned that relations betwixt Dublin and Stormont could go "untenable" if problems with the Northern Ireland Protocol could not beryllium resolved.
He called connected the EU to "change its tune" connected the protocol, which was agreed by the UK and EU to debar a hard borderline successful Ireland.
It does that by keeping Northern Ireland successful the EU's azygous marketplace for goods.
That has created a caller commercialized borderline successful the Irish Sea, which is powerfully opposed by unionists successful Northern Ireland.
"If the Irish authorities persists successful harming our narration with the remainder of the United Kingdom done this protocol past of people that has an interaction connected our narration with Dublin," said Sir Jeffrey.
"We are expected to run arsenic mean connected a north-south ground - that is not a tenable presumption and not 1 I mean to proceed with if we cannot resoluteness the issues astir the protocol and bash truthful quickly."
The DUP person said helium told the taoiseach that unionists' concerns that the protocol was having an antagonistic effect connected Northern Ireland were "certainly not diminishing".
He cited the "harm that it's doing to commercialized betwixt Great Britain and Northern Ireland" and the "political harm" it could origin up of adjacent year's Stormont assembly election.
"We request to code those issues and bash truthful rapidly - we request to region the borderline that has developed betwixt GB and Northern Ireland successful trading terms," helium said.
Speaking aft the meeting, Mr Martin said helium would proceed to talk to unionists astir their worries successful narration to the protocol.
He called for a absorption connected maintaining relations betwixt Northern Ireland and the Republic of Ireland.
"It would beryllium atrocious if determination was to beryllium immoderate disruption of that progressive work," helium said.
"I judge from a unionist position that they person genuine concerns.
"We don't needfully hold that they're ones that can't beryllium flooded - we'd person a antithetic position to that - but I admit the sincerity of the position that has been articulated to us.
"Europe wants to assistance present but determination needs to beryllium precise wide presumption from the UK broadside successful presumption of wherever they spot the solution of this."
On Thursday the Northern Ireland Protocol was a cardinal taxable of treatment erstwhile French President Emmanuel Macron visited Dublin, wherever helium met some Mr Martin and Irish President Michael D Higgins.
In the past Mr Macron has ruled retired immoderate renegotiation of the Brexit deal.
During his sojourn to Áras an Uachtaráin, the Irish president's residence, Mr Macron wrote successful the guestbook that Ireland "occupies a precious spot successful the bosom of the European dream".
Mr Macron's enactment explained that France would stay a "faithful person for the future".
In June, Sir Jeffrey's predecessor arsenic DUP person Edwin Poots visited Dublin and met Mr Martin on with DUP workfellow Paul Givan, who has since go archetypal curate of Northern Ireland.
Mr Poots said Mr Martin recognised the "genuine concerns successful unionist and loyalist communities astir the protocol".
But Mr Poots was ousted wrong 50 days of becoming DUP person and was replaced by Sir Jeffrey.