ARLENE Foster has said it is "simply not the case" that her party is boycotting north-south political meetings in protest at the Northern Ireland Protocol.
The DUP leader was speaking as other executive parties held a series of meetings yesterday to discuss two DUP no-shows at sectoral meetings of the North South Ministerial Council in recent weeks.
As Mrs Foster was addressing the Assembly, Sinn Féin President Mary Lou McDonald told a Stormont press conference that the DUP could not "cherry pick" from the Good Friday Agreement.
Mrs McDonald urged the party to clarify whether it will participate in future north-south political meetings.
SDLP leader Colum Eastwood also accused the DUP of "childish" behaviour.
On Friday SDLP infrastructure minister Nichola Mallon said a meeting with Irish transport minister Eamon Ryan was cancelled at the last minute after the DUP failed to nominate a unionist minister to attend.
One accompanying minister from the opposing political view must attend North South Ministerial Council meetings to allow them to proceed.
In February, the DUP warned that north-south relationships will be "impacted" as part of its political campaign to oppose the Northern Ireland Protocol, which governs post-Brexit trading arrangements on the Irish Sea.
The party also pledged to oppose all protocol-related measures in the assembly.
But Mrs Foster denied her party was "refusing" to attend meetings between the executive and Irish government.
"I spoke with the Taoiseach on Friday week ago by telephone," she told MLAs.
She added: "Just to be clear, the Northern Ireland Protocol is not part of the North South Ministerial Council.
"As we have outlined some weeks ago, north-south relationships will of course be affected by the fact that the protocol is in place because it has damaged east-west relationships and we need to sort it out.
"We need to get rid of the protocol so that we can continue to have relationships with our nearest neighbour in the appropriate way in the future so that the constitutional and economic position of Northern Ireland is something that every community can benefit from as opposed to the dreadful situation that we currently find ourselves in."
Mrs Foster added: "I have made it clear at all times that I and colleagues will act in the interests of the people of Northern Ireland and in accordance with all of our ministerial responsibilities and indeed the pledge of office as we have indicated."
Mrs McDonald was in Belfast for meetings with other Stormont Executive parties.
A meeting with the DUP did not happen but the Sinn Féin leader insisted it would take place in the near future.
"You can't cherry pick the Good Friday Agreement," she said.
She added: "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."
Mr Eastwood said it was "disappointing" that the DUP had not met his party yesterday to discuss the issue.
"I think this in-and-out approach in terms of their engagement with political institutions is childish and it needs to stop," he said.
Alliance MLA Andrew Muir said: "Really the solution to these things is more co-operation rather than less, and the politics of veto and blocking things is not what Northern Ireland needs at this time.".