DUP leader Arlene Foster has rejected Fianna Fáil leader Micheal Martin's criticism of the Stormont Executive, branding it offensive and unjustified.
At the weekend, Mr Martin urged the Irish and British governments to directly intervene in Northern Ireland, claiming a DUP/Sinn Féin "stranglehold" on the institutions had caused "immense damage".
Stormont First Minister Mrs Foster questioned Mr Martin's grounds for criticising political leaders north of the border when, in the Republic, a Government has still yet to be formed in the wake of February's general election.
"If it wasn't so offensive it would probably be quite funny," Mrs Foster said.
"Here is a man who is part of a political jurisdiction that 53 days after a general election can't form a Government, yet he spends his time making comments about a different country.
"He really should concentrate on forming a Government in his own country."
At a party Assembly election campaign event outside Titanic Belfast on Monday, Mrs Foster also responded to Ulster Unionist leader Mike Nesbitt's claim that she and Martin McGuinness were "arrogant" for characterising the race for the first minister's job as only between the DUP and Sinn Féin.
"We don't take any votes for granted and I think if you have seen the way I have been criss-crossing the country since I became first minister I am not taking anybody for granted," she said.
"Quite the contrary, if anybody's arrogant in this race it's him (Mr Nesbitt)."
Addressing his party's annual commemoration of the 1916 Easter Rising at Arbour Hill in Dublin on Sunday, Mr Martin said the British and Irish governments needed to intervene at Stormont.
"We need direct engagement by both the Irish and British governments to end the stranglehold in Stormont by two parties," he said.
"This is doing immense damage to public support for the institutions and public engagement in politics."
He also called for an overhaul in the North-South bodies set up under the Good Friday Agreement.
Mrs Foster said the DUP and Sinn Féin led the last Executive because they had secured the most votes at the last Assembly election.
"It's not up to Micheál Martin to tell the people of Northern Ireland how to elect their government," she said.