An important North South meeting on rural development and agriculture had to be cancelled while DUP members grappled over the party's leadership.
Writing online, Deputy First Minister Michelle O'Neill revealed the North South Ministerial Council (NSMC) meeting was cancelled as DUP politicians would not attend.
The party ousted its leader Arlene Foster following days of speculation and internal struggle.
In a statement, pushed on Friday (April 30) Foster said she would step down as the party's leader on May 28, and as First Minister at the end of June.
"The scheduled meeting of ministers North South on rural development and agriculture was cancelled as no DUP Minister would attend," O'Neill said.
"The North South dimension is central to the Good Friday Agreement and there is no alternative. Put simply these hare-brained antics are juvenile."
The Republic's Miniter for Agriculture, Food and the Marine Charlie McConalogue, who was due to meet Minister Poots, said he was "disappointed" the scheduled meeting did not take place.
"This engagement is crucial to strengthening North South ties. I urge all sides to work together for the betterment of our farmers and wider communities. We work stronger when we work together," he said.
Third cancelled meeting in two months
It's the third time in just two months that North South meetings have not been able to proceed because of DUP Ministers' failure to attend.
The first meeting effected was due to take place on March 31, to discuss languages.
The second meeting involved Northern Ireland Infrastructure Minister Nichola Mallon, and the Republic's Minister for Transport, Climate, Environment and Communications, Eamon Ryan.
However, Economy Minister Dianne Dodds, who is also a DUP member, did meet with Leo Varadkar on April 21.
The North South Ministerial Council was established following the Good Friday Agreement in 1998 to develop consultation, cooperation and action on the island.
Meetings cover six areas of cooperation including; health; transport; education; environment; agriculture; and tourism. Common policies and approaches are agreed but implemented separately in each jurisdiction.
Ministers from Northern Ireland must be accompanied by a second Northern Ireland minister with an opposing political view.
Important North South agri-food issues
Stormont Agriculture Committee chairman Declan McAleer said he was "deeply regrettable" that this action had come at a time when important discussions were taking place regarding the island's agri-food sector.
"Regardless of one's political perspective, agriculture - and in particular agri-food and dairy processing - has always been an island-wide industry. North South trade in agri-food amounts to around €1.3 billion a year and virtually all the food produced here would be deemed as 'mixed origin'," he said.
"In addition to trade, there are major issues such as TB, ammonia and animal health that have major influences on the the agriculture industry and its is essential that both parts of the island are coordinated on these major issues because what happens in one jurisdiction directly impacts on the other.
"It is also incredible that at a time when we are lobbying for the North to be included in the PGI bid for Irish Grass-fed Beef, that the DUP are undermining the very institutions that could help make this possible.
"At this crucial time, as we cautiously emerge from the Covid pandemic against a backdrop of an enforced Brexit that has caused so much damage to the industry, the last thing rural communities need is for the DUP to bring their internal party turmoil into the North South arrangements for agriculture and rural affairs."
The DUP has been contacted for response.