Sir Jeffrey Donaldson has said there is nothing to suggest the Dublin government plans to breach the Good Friday Agreement by involving itself in the north's internal affairs.
The Lagan Valley MP was speaking to The Irish News following reports that the DUP would walk away from the Stormont negotiations if the Irish government proposed measures for resolving the talks impasse.
Sir Jeffrey said he was responding solely to calls from SDLP leader Colum Eastwood for the two governments to publish their plans for breaking the eight-month political deadlock.
The DUP MP, who famously walked out of the negotiations that led to the 1998 Good Friday Agreement, told the News Letter his party "would not countenance" proposals from Dublin that affected Northern Ireland's internal affairs.
"Such a proposition would be a fundamental breach of the Good Friday Agreement and the three-stranded approach and would bring the talks to an end," he said.
"They cross that line, the talks are over."
But Sir Jeffrey has conceded that there is nothing to indicate the Dublin government has any plans to table suggestions for the talks that would clearly break the three-stranded approach, which relates respectively to Northern Ireland internally; the north-south dimension; and relations between the Republic and Britain.
"To date, there has been adherence to the rules of engagement and I hope that adherence will continue," he said.
"We all want to find a resolution, so let's not make the situation even more difficult by breaking the rules of engagement."
The Department of Foreign Affairs declined to comment on the Lagan Valley MP's comments. However, SDL leader Colum Eastwood labelled Sir Jeffrey's remarks "childish" and "out-of-hand".
The Foyle MLA said Dublin had "every right to make constructive contributions" on how the impasse could be overcome.
“We have called on all parties to put their cards on the table in relation to the challenges we face – if the DUP is so keen to minimise the role of the Irish government, they should use their mandate to make a deal and restore the institutions," he said.
"It is incredibly frustrating that any time we have a hint of progress, the DUP Westminster group makes a negative intervention – it begs the very serious question: who is in the driving seat in the DUP?"
