Stormont First Minister Arlene Foster has denied unionists are boycotting meetings with the Irish Government as part of a plan to overthrow the Northern Ireland protocol.
The Democratic Unionist Party (DUP) leader described as "misplaced" and "quite mischievous" claims of an unspoken campaign to scupper North/South Ministerial Council (NSMC) meetings by not putting forward unionist Ministers.
On Friday, a meeting involving Minister for Transport Eamon Ryan and his counterpart in the North Nichola Mallon had to be abandoned because, as Ms Foster said, "it did not suit" the nominated unionist Minister to attend.
It was the second such meeting in two weeks "to be obstructed in this way", according to Justice Minister and Alliance Party leader Naomi Long.
But speaking in the Northern Ireland Assembly on Monday, Ms Foster rejected allegations "that we are refusing, in inverted commas, to attend meetings between the Northern Ireland Executive and the Government of the Republic of Ireland".
“That is simply not the case,” she said.
But she warned North/South relations “will of course be affected by the fact that the protocol is in place, because of its damage to east/west relationships.”
“We need to sort it out and we need to get rid of the protocol so we can continue to have relationships with our nearest neighbour in the appropriate way in the future,” she added.
Unionists have united for a five-point plan to get rid of the protocol, a post-Brexit arrangement which puts a de facto trade barrier for goods in the Irish Sea to prevent any need for a hardening of the Border on the island of Ireland.
Ms Mallon has accused the DUP of engaging in a "deliberate act" of obstructing North-South co-operation as part of its plan, adding that it was undermining the Belfast Agreement.
Responding to remarks by the European Commission vice-president in charge of Brexit, Maros Sefcovic, that the protocol was the only way to protect the peace deal, Ms Foster said Mr Sefcovic "either wilfully misunderstands the Belfast Agreement or is misrepresenting it for his own ends".
"There is a need for those in Europe, in London, in Dublin as well, to listen to the voices of those of us who will not have the protocol, because it is damaging the economy of Northern Ireland," she said.
"But more than that, it is damaging our citizenship here in Northern Ireland as equal citizens of the United Kingdom, because we cannot partake in the internal market of the United Kingdom."
Asked if the North's DUP Economy Minister Diane Dodds would attend a scheduled NSMC meeting due to take place this week, Ms Foster would only say her party was "fully aware" of its legal ministerial responsibilities.
Ms Mallon had gone ahead with last Friday’s meeting “despite the fact she had been told it did not suit the nominated person who would accompany with her” under the cross-community rules of the meetings, she said.
Ms Foster said the agenda and papers for the meeting had also not been agreed by her office.
NSMC councils have to “proceed by agreement” and “I very much hope agreement and consensus will be sought by those Ministers setting up North/South Ministerial Council meetings in future”, she added.
The DUP leader met businesses in the North on Friday to discuss the costs they are suffering as a result of Brexit.
“I was, I have to say, alarmed at the extra costs that those businesses are having to incur,” she told the Assembly.
“Some of course are passing them on to consumers and to clients, which is very worrying as well.”
Ms Foster said there has been a “reduction in choice and an increase in costs”, which she blamed on the protocol “being implemented in the fashion that it has been”.
Checks on goods between Britain and the North are “completely disproportionate to the risk to the [EU] single market”, she said.
“I mean, the amount of damage being done to our businesses is quite incalculable,” the First Minister added.
Sinn Féin leader Mary Lou McDonald warned any refusal by unionists to participate in NSMC meetings “raises very serious questions, not just for the DUP, but for all of us”.
“You can’t cherry pick the Good Friday Agreement,” she said, after meetings with other Stormont Executive parties in Belfast.
“Political progress, stability and inclusion relies on all of the institutions of the Good Friday Agreement working and working well.
“The North-South piece is absolutely essential and that means that unionists of all hues have to participate in those meetings. I think it would obviously be hugely problematic if there was any suggestion that any strand of unionism was stepping back from that or causing a problem with the North-South mechanism.”